Characterization of Ga2O3

Aim

Ga₂O₃ is an ultra-wide band gap semiconductor with a great application potential. The contactless characterization of defect related transitions with high sensitivity is still challenging.

Solution

Contactless surface photovoltage (SPV) spectroscopy in the dc (Kelvin probe, direct measurement of the contact potential difference, DCPD) and ac (modulated regime) modes provides information about transitions energies and direction of charge separation in a wide spectral range from near infrared (< 0.5 eV) up to the deep ultraviolet (> 6 eV) at high sensitivity. Furthermore, the same perforated electrode can be applied for measurements in dc and ac modes with a charge amplifier (figure 1).

Application example

Figure 2 shows an example for the measurement of a (negative) DCPD spectrum and the spectrum of the modulated SPV amplitude (in a logarithmic scale) on the same place of a b-Ga₂O₃ crystal. Transitions at the band gap of b-Ga₂O₃ at 4.8 eV and defect transitions at 1.6, 2.3, 3.2, 4.0, 4.4 and 4.6 eV are well distinguished whereas the sensitivities for measurements in the dc and ac modes can be rather different for different transitions.