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PICTSStudio user friendly and advanced software for defect investigations The PICTSStudio offers features for defect investigation like, Operation and configuration area Results/charting View of single transients and temperature dependent curves Evaluation of activation energy and capture cross sections via Arrhenius plot Get in touch Do not hesitate to contact us – we are available to assist you with any inquiries or requests. Use our inquiry tool or reach out via email: sales @ freiberginstruments.com

Materials Electrical properties and defects of a large variety of semiconductor materials, devices and dielectric materials can be investigated contact less and destruction free with our advanced method MDP. Electrical properties and defects of a large variety of semiconductor materials, devices and dielectric materials can be investigated contact less and destruction with our advanced method MDP. MDP is a contact less and destruction free method, so that no sample preparation is needed. The only exception is that for investigations of the bulk properties of for example silicon samples a surface passivation is preferred. There are no restrictions on the sample shape or size starting with nano material powders up to 12" wafers. Apparently all semiconductors on the market can be investigated. Starting with a variety of electronic grade- and multicrystalline silicon. Due do the high sensitivity even the quality of thin epitaxial layers and strained silicon can be characterized. Investigations have been carried out on GaAs, InP, SiC, GaN, Ge and other compound semiconductors. The list is constantly expanding. So far few limitations are known. Matching Products MDP series MDPmap Precision Lifetime Charachterization with Exceptional Sensitivity Learn more MDP series MDPspot Quick and Simple Lifetime Measurement Made Easy Learn more MDP series MDpicts pro High-Resolution, Temperature-Dependent Lifetime Measurement System for Precise Material Characterization Learn more MDP series MDPpro 850+ Advanced Solution for Quality Control of Monocrystalline Silicon Ingots, Bricks, and Wafers Learn more MDP series MDPlinescan Versatile OEM Unit for Lifetime Measurements on Silicon Samples, from Bricks to Processed Wafers Learn more MDP series MDpicts Temperature-Dependent Lifetime Measurement System for Advanced Material Analysis Learn more RES series RESmap High-Precision Resistivity Mapping System for Accurate Material Analysis Learn more Get in touch Do not hesitate to contact us – we are available to assist you with any inquiries or requests. Use our inquiry tool or reach out via email: sales @ freiberginstruments.com

Penetration depth of different laser wavelength in silicon In silicon laser light with different wavelength has different penetration depth, hence the right laser should be used for different applications, e.g. for epitaxial layers or investigations of the surface smaller wavelength are ideal. An approximati Penetration depth of different laser wavelength in silicon The microwave detected photoconductivity measures the photoconductivity after the irradiation of the sample with light. Usually the light should have an energy that is higher than the bandgap, so that electrons and holes are created. For silicon this means that a wavelength smaller than 1100 nm should be used. If the surface should be investigated or thin epitaxial layers, it might be useful to use even UV or blue light, which has a much smaller penetration depth in silicon. Figure 1 shows the penetration depth in silicon versus the wavelength and gives the user a hint, which wavelength is most useful for his application. Fig. 1: penetration depth in silicon versus wavelength Matching Products MDP series MDPmap Precision Lifetime Charachterization with Exceptional Sensitivity Learn more MDP series MDPspot Quick and Simple Lifetime Measurement Made Easy Learn more MDP series MDpicts pro High-Resolution, Temperature-Dependent Lifetime Measurement System for Precise Material Characterization Learn more MDP series MDPpro 850+ Advanced Solution for Quality Control of Monocrystalline Silicon Ingots, Bricks, and Wafers Learn more MDP series MDPlinescan Versatile OEM Unit for Lifetime Measurements on Silicon Samples, from Bricks to Processed Wafers Learn more MDP series MDpicts Temperature-Dependent Lifetime Measurement System for Advanced Material Analysis Learn more RES series RESmap High-Precision Resistivity Mapping System for Accurate Material Analysis Learn more Get in touch Do not hesitate to contact us – we are available to assist you with any inquiries or requests. Use our inquiry tool or reach out via email: sales @ freiberginstruments.com

MD-PICTS MD-PICTS is a modification of MDP, where temperature dependent measurements of the defect part of the transient are accomplished. MD-PICTS – microwave detected photo induced current transient spectroscopy MD-PICTS is a modification of MDP, where temperature dependent measurements of the defect part of the transient are accomplished. This allows for a spatially resolved defect characterization. Similar to DLTS (deep level transient spectroscopy), the activation energy and the capture cross section of the defects can be determined. However, in contrast to DLTS, no contacts are needed. This is extremly valuable for defect identification and material quality improvement. Fig. 1: example of a MD-PICTS spectrum of different tempered Cz—Si wafers If you want to learn more about this method read: B. Grundig-Wendrock, M. Jurisch, and J. R. Niklas, Materials Science and Engineering B-Solid State Materials for Advanced Technology 91, 371-375 (2002) S. Hahn, F. Beyer, A. Gällström, P. Carlsson, A. Henry, B. Magnusson, J. R. Niklas, and E. Janzen, Materials Science Forum 600-603, 405-408 (2009) K. Dornich, K. Niemietz, Mt. Wagner, J.R. Niklas, Material Science in Semiconductor Processing, Elsevier, 241-245 Bastian Berger, Nadine Schüler, Sabrina Anger, Bianca Gründig-Wendrock, Jürgen R. Niklas, Kay Dornich, Contactless electrical defect characterization in semiconductors by microwave detected photo induced current transient spectroscopy (MD-PICTS) and microwave detected photoconductivity (MDP) Matching Products MDP series MDPmap Precision Lifetime Charachterization with Exceptional Sensitivity Learn more MDP series MDPspot Quick and Simple Lifetime Measurement Made Easy Learn more MDP series MDpicts pro High-Resolution, Temperature-Dependent Lifetime Measurement System for Precise Material Characterization Learn more MDP series MDPpro 850+ Advanced Solution for Quality Control of Monocrystalline Silicon Ingots, Bricks, and Wafers Learn more MDP series MDPlinescan Versatile OEM Unit for Lifetime Measurements on Silicon Samples, from Bricks to Processed Wafers Learn more MDP series MDpicts Temperature-Dependent Lifetime Measurement System for Advanced Material Analysis Learn more RES series RESmap High-Precision Resistivity Mapping System for Accurate Material Analysis Learn more Get in touch Do not hesitate to contact us – we are available to assist you with any inquiries or requests. Use our inquiry tool or reach out via email: sales @ freiberginstruments.com

Comparison to µ-PCD and QSSPC Among carrier lifetime experiments, it is still one of the biggest problems to understand widely contradicting results as obtained by different experimental methods. With our novel simulation tool it is possible to simulate steady state and non stead Besides MDP the two most important contact less lifetime measuring methods are QSSPC (quasi steady state photoconductivity) and µ-PCD (microwave detected photoconductive decay). Currently one of the biggest problems in the photovoltaic industry is to make the deviating lifetime measurement results of the different methods comparable. With our novel simulation tool it is possible to simulate steady state and non steady state measurements, so that a comparison is possible. µ-PCD The µ-PCD method typically operates at very high injections with a very short light pulse of only 200 ns. The minority carrier lifetime is determined via the photoconductive decay, similar to MDP. µ-PCD detects the photoconductivity by measuring the reflection of a microwave at the sample, which makes this method less sensitive than MDP. QSSPC QSSPC detects the changes in permeability of the sample and therefore the conductance via the coupling of the sample by a coil to a radio-frequency bridge. The exciting light is tuned down slowly, so that the sample is always in a quasi steady state. A further difference to MDP is the use of a flash-light with a hole light spectrum, in stead of monochrome laser light as the excitation source. Figure 1 displays the injection ranges in which the different lifetime measuring methods typically operate. It becomes clear that MDP surpasses the other methods, because it enables to measure over 7 decades of injection. If the measurement results of these different methods are compared, the injection, excitation wavelength, penetration depth of the microwave, the carrier profile and the different behaviour of traps, that depends on the duration of the light pulse, has to be taken into consideration. For more details read: [1] T. Hahn, Thesis, TU Bergakademie, 2009 Fig. 1: Comparison of MDP, µPCD and QSSPC with respect to their typical injection ranges Matching Products MDP series MDPmap Precision Lifetime Charachterization with Exceptional Sensitivity Learn more MDP series MDPspot Quick and Simple Lifetime Measurement Made Easy Learn more MDP series MDpicts pro High-Resolution, Temperature-Dependent Lifetime Measurement System for Precise Material Characterization Learn more MDP series MDPpro 850+ Advanced Solution for Quality Control of Monocrystalline Silicon Ingots, Bricks, and Wafers Learn more MDP series MDPlinescan Versatile OEM Unit for Lifetime Measurements on Silicon Samples, from Bricks to Processed Wafers Learn more MDP series MDpicts Temperature-Dependent Lifetime Measurement System for Advanced Material Analysis Learn more RES series RESmap High-Precision Resistivity Mapping System for Accurate Material Analysis Learn more Get in touch Do not hesitate to contact us – we are available to assist you with any inquiries or requests. Use our inquiry tool or reach out via email: sales @ freiberginstruments.com

Microwave detected photoconductivity The advanced method MDP is suited for defect investigation and mapping of wafers and ingotsWith its extraordinary sensitivity, resolution and speed MDP enables injection dependent measurements as well as mapping with a very high resolution. The novel method MDP is well suited for both, defect investigation by e.g. injection dependent minority carrier lifetime measurements, as well as mapping of wafers or even bricks for inline metrology. It exceeds his competitors µPCD (microwave detected photoconductivity decay) and QSSPC (quasi steady state photo conductance) in terms of sensitivity, resolution and speed. The photoconductivity, which is closely related to the diffusion length is measured by microwave absorption during and after the excitation with a rectangular laser pulse. Figure 1 displays the measurement principle for MDP and MD-PICTS measurements. generation of free carriers traps are filled with carriers recombination of free carriers thermal reemission of trapped carriers temporally shifted recombination of reemitted carriers A microwave with about 10 GHz is generated in a frequent stable microwave-generator and split into a reference and measurement part. With an attenuator the power can be adjusted and ranges typically from 1 to 100 MW. The sample is situated just outside the cavity and is part of the measurement system. A special iris in the cavity-wall allows the microwave field to penetrate the sample. Thus, the complex dielectric constant of the sample influences the resonant frequency and the loss properties of the cavity. Microwave absorption by excess charge carriers is detected with an IQ-detector. The sample is placed on an x-y-table, allowing theoretically every sample size and to move the sample in the x-y-plane. For temperature dependent MD-PICTS measurements the sample has to be part of a cryostat system, so that the sample size is currently limited, but apart from that it is principally the same measurement system. Fig. 1: Energy scheme of the measurement principle Fig. 2: Exemplary signal Fig. 3: setup for MDP and MD-PICTS The high detection sensitivity enabled by this technique allows the application even of weak laser pulses with an intensity of µW to mW and with unlimited pulse duration. Hence it is possible to measure in a non- or steady state regime and to continously vary the pulse length from 100 ns to several ms. The resolution of this system is only limited by the diffusion length of the sample. Besides advantages in speed and sensitivity, a major advantage of MDP is the ability to measure photoconductivity and minority carrier lifetime simultaneously. Accordingly more parameters can be extracted from each measurement, like diffusion length, mobility and even trapping dynamics. Fig. 4: Exemplary lifetime map of a mc-Si wafer Fig 5: Exemplary photoconductivity map of a mc-Si wafer Matching Products MDP series MDPmap Precision Lifetime Charachterization with Exceptional Sensitivity Learn more MDP series MDPspot Quick and Simple Lifetime Measurement Made Easy Learn more MDP series MDpicts pro High-Resolution, Temperature-Dependent Lifetime Measurement System for Precise Material Characterization Learn more MDP series MDPpro 850+ Advanced Solution for Quality Control of Monocrystalline Silicon Ingots, Bricks, and Wafers Learn more MDP series MDPlinescan Versatile OEM Unit for Lifetime Measurements on Silicon Samples, from Bricks to Processed Wafers Learn more MDP series MDpicts Temperature-Dependent Lifetime Measurement System for Advanced Material Analysis Learn more RES series RESmap High-Precision Resistivity Mapping System for Accurate Material Analysis Learn more Get in touch Do not hesitate to contact us – we are available to assist you with any inquiries or requests. Use our inquiry tool or reach out via email: sales @ freiberginstruments.com

Simulation of carrier profiles For measurements at thick samples like ingots, it is very important to simulate the carrier depth profile, that developes in the sample. The measured lifetime is strongly effected by this profile, so that this effect has to be taken into account. Simulation of carrier profiles in thick samples The measurement of thick samples as bricks leads to new questions and problems. One of these questions is how the carrier profiles that develops in a sample effect the lifetime measurements. To solve this problem, we developed a simulation tool for the modelling of carrier profiles. This tool consists of a partial differential equation system of the transport equations for electrons and holes and the Poisson equation. \(\frac{\partial}{\partial t}n(x,t)=\frac{\partial}{\partial x} \left[ -\mu_nn(x,t)\frac{\partial}{\partial x} \Psi(x,t) + D_n\frac{\partial}{\partial x}n(x,t) \right]+ G^o(x,t) - U(x,t)\) \(\frac{\partial}{\partial t}p(x,t)=\frac{\partial}{\partial x} \left[ \mu_pp(x,t)\frac{\partial}{\partial x} \Psi(x,t) + D_p\frac{\partial}{\partial x}p(x,t) \right]+ G^o(x,t) - U(x,t)\) \(\frac {\partial^2}{\partial x^2} \Psi (x,t) = -\frac{q}{\in_0\in_y} \left[ -n(x,t) + p(x,t)_\text{dot} \right]\) Transport equations for electrons and holes + Poisson equation The simulations for measurements with a long (typical MDP condition) or a very short light pulse (typical µ-PCD conditions) at thick unpassivated samples are shown in figure 1 and 2. It becomes clear, that the carrier profile of a long light pulse expands through a large volume of the sample, where as the carrier profile of the only 200 ns long light pulse is very surface near. This has a direct effect on the measured lifetime, since the surface recombination has a much stronger effect on the µ-PCD measurements. Figure 3 shows the quantitative effect of the surface recombination on the effective lifetime for both measurement conditions. The MDP measurements are less prone to the surface effect, so that MDP measurements are more suited for the investigation of bulk properties. Accordingly µ-PCD is an ideal method to investigate the surface properties of a sample. Fig.3: evaluated effective lifetimes as a function of bulk lifetime for both methods Matching Products MDP series MDPmap Precision Lifetime Charachterization with Exceptional Sensitivity Learn more MDP series MDPspot Quick and Simple Lifetime Measurement Made Easy Learn more MDP series MDpicts pro High-Resolution, Temperature-Dependent Lifetime Measurement System for Precise Material Characterization Learn more MDP series MDPpro 850+ Advanced Solution for Quality Control of Monocrystalline Silicon Ingots, Bricks, and Wafers Learn more MDP series MDPlinescan Versatile OEM Unit for Lifetime Measurements on Silicon Samples, from Bricks to Processed Wafers Learn more MDP series MDpicts Temperature-Dependent Lifetime Measurement System for Advanced Material Analysis Learn more RES series RESmap High-Precision Resistivity Mapping System for Accurate Material Analysis Learn more Get in touch Do not hesitate to contact us – we are available to assist you with any inquiries or requests. Use our inquiry tool or reach out via email: sales @ freiberginstruments.com

Lifetime simulations To gain a better understanding of lifetime measurements and to achieve a better comparability between different measuring methods, it is necessary to perform simulations. Generalized rate equations for lifetime simulations This numerical tool is based on a generalized rate equation system, which is solved for all possible transitions between the defect levels in the forbidden gap and the bands of a semiconductor. The only approximation is, that no interactions between defect levels are included. This is a valid approximation, since the defect density in silicon is typically low. The applied rate equation system describes the time dependent change of carrier concentrations in the conduction and valence band, as well as in defect levels. In this equation system the optical and thermal generation rates, the band to band and Auger recombination rates and the carrier capture and emission rates from all defects (Cj, Dj, Ej, Fj) are included. The transition rates are described without any approximations. \(\dot{n} = G^0_{BB} + G^th_{BB} + \sum_{j}(C_j - D_j) - R_{BB} - R_{Aug}\) \(\dot{p} = G^0_{BB} + G^th_{BB} + \sum_{j}(F_j - E_j) - R_{BB} - R_{Aug}\) \(\dot{n}_{Tj} = D_j + E_j) - C_j - F_j\) Fig. 1: energy scheme of all transition rates that are included into the simulations From the simulated time dependent carrier concentrations the photoconductivity can be calculated using the mobility model of DORKEL and LETURCQ [2] . The minority carrier lifetime can be extracted from the transient of the photoconductivity after Gopt is set to zero. advantages compared to SRH simulations or PC1D lifetime is not a parameter, but a direct result non steady state can be simulated as well an arbitrary number j of defect levels can be included The numerical simulation tool is suited for simulation of injection and temperature dependent measurements, for investigating the trapping effect on lifetime and photoconductivity and for the comparison of MDP and µPCD or other measurement conditions. Summarizing, this simulation tool enables to make lifetime measurements more comparable and to achieve a better understanding of the results. Fig. 2: varying Et Fig. 3: varying Nt Fig. 4: varying σp More information about these simulations can be found in: [1] T. Hahn, Thesis, TU Bergakademie, 2009 [2] J. M. Dorkel and P. Leturcq, Solid-State Electronics 24, 821-825 (1981) Matching Products MDP series MDPmap Precision Lifetime Charachterization with Exceptional Sensitivity Learn more MDP series MDPspot Quick and Simple Lifetime Measurement Made Easy Learn more MDP series MDpicts pro High-Resolution, Temperature-Dependent Lifetime Measurement System for Precise Material Characterization Learn more MDP series MDPpro 850+ Advanced Solution for Quality Control of Monocrystalline Silicon Ingots, Bricks, and Wafers Learn more MDP series MDPlinescan Versatile OEM Unit for Lifetime Measurements on Silicon Samples, from Bricks to Processed Wafers Learn more MDP series MDpicts Temperature-Dependent Lifetime Measurement System for Advanced Material Analysis Learn more RES series RESmap High-Precision Resistivity Mapping System for Accurate Material Analysis Learn more Get in touch Do not hesitate to contact us – we are available to assist you with any inquiries or requests. Use our inquiry tool or reach out via email: sales @ freiberginstruments.com

Defect properties For the efficiency of solar cells the properties of a defect and its impact on the material quality are of great importance. Defect properties The properties of a defect and its impact on the material quality can be described by three main parameters: defect concentration N T capture cross sections for electrons and holes σ n , σ p activation energy E T All these properties are part of the simulation models we use and they can be measured beside the defect concentration with the temperature dependent method MD-PICTS . Fig. 1: Energy scheme of a defect and its important parameters Matching Products MDP series MDPmap Precision Lifetime Charachterization with Exceptional Sensitivity Learn more MDP series MDPspot Quick and Simple Lifetime Measurement Made Easy Learn more MDP series MDpicts pro High-Resolution, Temperature-Dependent Lifetime Measurement System for Precise Material Characterization Learn more MDP series MDPpro 850+ Advanced Solution for Quality Control of Monocrystalline Silicon Ingots, Bricks, and Wafers Learn more MDP series MDPlinescan Versatile OEM Unit for Lifetime Measurements on Silicon Samples, from Bricks to Processed Wafers Learn more MDP series MDpicts Temperature-Dependent Lifetime Measurement System for Advanced Material Analysis Learn more RES series RESmap High-Precision Resistivity Mapping System for Accurate Material Analysis Learn more Get in touch Do not hesitate to contact us – we are available to assist you with any inquiries or requests. Use our inquiry tool or reach out via email: sales @ freiberginstruments.com

Diffusion length Diffusion length The diffusion length is the average distance that the excess carriers can cover before they recombine. Diffusion length depends on the lifetime and mobility of the carriers. \(L = \sqrt{D\tau}\) Note: Diffusion factor (D) is not a constant, but depents on the carrier mobility. \(D = \mu \cfrac{kT}{e}\) For the resolution of every electrical measurement the diffusion length is the limitation. For a measurement of high quality silicon samples a maximal resolution of about 1 mm can be achieved. Matching Products MDP series MDPmap Precision Lifetime Charachterization with Exceptional Sensitivity Learn more MDP series MDPspot Quick and Simple Lifetime Measurement Made Easy Learn more MDP series MDpicts pro High-Resolution, Temperature-Dependent Lifetime Measurement System for Precise Material Characterization Learn more MDP series MDPpro 850+ Advanced Solution for Quality Control of Monocrystalline Silicon Ingots, Bricks, and Wafers Learn more MDP series MDPlinescan Versatile OEM Unit for Lifetime Measurements on Silicon Samples, from Bricks to Processed Wafers Learn more MDP series MDpicts Temperature-Dependent Lifetime Measurement System for Advanced Material Analysis Learn more RES series RESmap High-Precision Resistivity Mapping System for Accurate Material Analysis Learn more Get in touch Do not hesitate to contact us – we are available to assist you with any inquiries or requests. Use our inquiry tool or reach out via email: sales @ freiberginstruments.com