Evaluation of Fe-βGa2O3 for Photoconductive Semiconductor Switching

• Published in: IEEE transactions on electron devices Vol. 71; no. 3; pp. 1535 - 1540
• Main Authors: Dowling, Karen M., Chatterjee, Bikramjit, Ghandiparsi, Soroush, Shao, Qinghui, Varley, Joel, Schneider, Joseph D., Chapin, Caitlin, Gottlieb, Miranda S., Leos, Laura, Sword, Michael, Harrison, Sara, Voss, Lars
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.03.2024; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Absorptivity; Carrier recombination; Dark current; Electric breakdown; Electrodes; Energy gap; ENGINEERING; Fe-doping; Gallium; Gallium oxide; Gallium oxides; High temperature; Insulators; Iron; Light emitting diodes; Optical variables measurement; Passivation; Photo-conductive switch; Photoelectric effect; Room temperature; Semiconductor device measurement; Sub bandgap illumination; Temperature effects; Temperature measurement
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2024.3352528

We present iron-doped beta gallium oxide (Fe-<inline-formula> <tex-math notation="LaTeX">\beta </tex-math></inline-formula>Ga2O3) as a candidate for photoconductive semiconductor switches (PCSSs) with sub-bandgap light. From a commercially available Fe-<inline-formula> <tex-math notation="LaTeX">\beta </tex-math></inline-formula>Ga2O3 wafer, we first did material characterization. This included measurements of absorption coefficient and dopant composition, carrier activation energy up to 200 °C, break down field of planar electrodes (limited from material passivation), and free carrier recombination lifetime, and thermal effects up to 203 °C on photocurrent with a 447 nm light emitting diode (LED) source. We then demonstrated pulsed operation of a Fe-<inline-formula> <tex-math notation="LaTeX">\beta </tex-math></inline-formula>Ga2O3 PCSS under different sub-bandgap wavelengths (355, 532, and 1064 nm) and sub-ns pulses. Fe-<inline-formula> <tex-math notation="LaTeX">\beta </tex-math></inline-formula>Ga2O3 is a candidate for high temperature PCSS with 355 nm responsivity of <inline-formula> <tex-math notation="LaTeX">7\times 10^{-{7}} </tex-math></inline-formula> A-cm/W-kV at room temperature and up to <inline-formula> <tex-math notation="LaTeX">5.5\times 10^{-{4}} </tex-math></inline-formula> A-cm/W-kV at 200 °C. From these investigations, we discuss a simple trap model to describe the illumination process of the PCSS. Fe-<inline-formula> <tex-math notation="LaTeX">\beta </tex-math></inline-formula>Ga2O3 has a high breakdown field and has moderate responsivity characteristics, but the dark current at high temperature leads to low photo-to-dark current ratio (PDCR). Regardless, we verify its potential as a PCSS material for harsh environment applications.