419. Electrical properties of vertical Cu2O/β-Ga2O3 (001) p-n diodes

Fig. 1 (a) Cross-sectional schematic of the vertical Cu2O/β-Ga2O3 heterojunction diodes. (b) XRD patterns of the sputtered Cu2O thin films at RT (sample1, red) and 600 °C (sample 2, blue).

Fig. 2 (a) Comparison of the forward J-V-Ron,sp characteristics for the fabricated Cu2O/β-Ga2O3 heterojunction diodes with different Cu2O films formed at RT (sample 1) and 600 °C (sample 2), respectively, in a linear scale. (b) Reverse J-V characteristics of sample 1 and sample 2. C-V and 1/C2-V characteristics results at 100 kHz for (c) sample 1 and (d) sample 2, respectively.

Fig. 3 Fitting results of forward J-V characteristics measured at 300 K for (a) sample 1 and (b) sample 2. (c) Temperature-dependent J-V characteristics from 300 to 480 K for sample 2. (d) Fitting results of J-V characteristics measured at 480 K for sample 2. The decrease in Φb measured from J-V characteristics is highlighted in the inset of (b).

Yun Jia, et al, AIP Adv. 13, 105306 (2023)
https://doi.org/10.1063/5.0168841

(1) At 300 K, trap-assisted tunneling dominates the regime because of the presence of defects in Cu2O or β-Ga2O3. While the bias voltage is low, the dominant mechanism governing carrier transport is interface recombination. As the temperature increases, however, thermionic emission becomes more important.
(2) Various p-type oxide materials, including NiO, Cu2O, Cr2O3, ZnCo2O4, and SnO, have been applied to the β-Ga2O3-based heterojunction diodes. Among these materials, Cu2O (cubic crystal) with a bandgap energy of about 2.1 eV is one of the promising candidates for an intrinsic p-type conductivity because of negatively charged Cu vacancies that create an acceptor level above the valence band maximum.
(3) The common Cu2O films are polycrystalline mixtures of the CuO phase and encompass several defects, which can act as sites for trapping, scattering, and recombination centers.
(4) The Cu2O thin films were deposited by sputtering from the Cu target in a mixture of Ar (9.9 sccm) and O2 (1.5 sccm) ambient at RT and 600 °C.
(5) Cu2O and β-Ga2O3 can potentially form an energetically favorable periodic coincidence lattice at the Cu2O/β-Ga2O3 interface, suggesting that the sputtering deposition is epitaxial.
(6) The coexistence of Cu4O3 (220) existed in the deposited Cu2O films can lead to the formation of grain boundaries in thin films.