Comparative Study of Low-Frequency Noise in Diodes Made of Ultra-Wide Band Semiconductors

In recent years, ultra-wide bandgap (UWBG) semiconductors have attracted increasing attention owing to the ever-increasing industry demand for high-power density electronics. Materials such as diamond, AlGaN, BN, and <i>β</i>-Ga₂O₃ emerged as viable alternatives to the well-established wide-bandgap technologies such as GaN and SiC. Low-frequency electronic noise produced by a device is an important metric. From one side, the level of low-frequency noise should be reduced for device applications in communications or sensors. On the other side, low-frequency noise can provide valuable information about the material quality and device reliability. The low-frequency noise includes the 1/f, flicker noise, and generation-recombination (G-R) noise with a Lorentzian-type spectrum (f is the frequency). Both 1/f and G-R noise are associated with material defects acting as trapping centers for the charge carriers. The latter can be used to understand the charge carrier dynamics and defects in materials. To some degree, the noise level can be used as a metric to assess the maturity of the material and device technology. We have conducted detailed noise studies in GaN vertical PIN diodes [1], high-current diamond diodes [2], <i>β</i>-(Al_xGa_1-x)₂O₃ Schottky barrier diodes [3], and NiO_x/<i> β</i>-Ga₂O₃ <i>p-n</i> heterojunction diodes [4]. At the presentation, we will compare the overall noise level in different UWBG technologies and comment on the effects of the material quality and device design. We will also describe the most interesting features observed in the noise spectra for some of the devices. Specifically, it was found that the noise of the diamond diodes is dominated by the 1/f and G-R noise. The G-R bulges are characteristic of diamond diodes with lower turn-on voltages. The characteristic trap time constants, extracted from the noise data, show a uniquely strong dependence on current. Interestingly, the performance of the diamond diodes improves with the increasing temperature. The noise spectral density of the β-(Al_xGa_1-x)₂O₃ diodes, at room temperature, reveals 1/f dependence, with superimposed Lorentzian bulges at the intermediate current regimes. At the intermediate current level, the Lorentzian component belongs to the random telegraph signal (RTS) noise. The RTS noise was attributed to the defects near the Schottky barrier affecting the local electric field and the potential barrier, which correspondingly impacts the electric current.<br/><br/>This work was supported by ULTRA, an Energy Frontier Research Center (EFRC) funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0021230.<br/><br/>[1] S. Ghosh, K. Fu, F. Kargar, S. Rumyantsev, Y. Zhao, and A. A. Balandin, “Low-frequency noise characteristics of GaN vertical PIN diodes—Effects of design, current, and temperature”, Appl. Phys. Lett., 119, 243505 (2021).<br/>[2] S. Ghosh, H. Surdi, F. Kargar, F. Koeck, S. Rumyantsev, S. Goodnick, R. J. Nemanich, and A. A. Balandin, “Excess noise in high-current diamond diodes”, Appl. Phys. Lett., 120, 062103 (2022).<br/>[3] S. Ghosh, D. H. Mudiyanselage, S. Rumyantsev, Y. Zhao, H. Fu, S. Goodnick, R. Nemanich, and A. A. Balandin, "Low-frequency noise in<i> β</i>-(Al_xGa_1-x)₂O₃ Schottky barrier diodes", Appl. Phys. Lett., 122, 212109, 2023.<br/>[4] S. Ghosh, D. H. Mudiyanselage, F. Kargar, Y. Zhao, H. Fu, and A. A. Balandin, "Temperature dependent low-frequency noise characteristics of NiO_x/<i> β</i>-Ga₂O₃ <i>p-n</i> heterojunction diodes", arXiv:2307.15659.