Majority and Minority Carrier Traps in NiO/β-Ga 2 O 3 p + -n Heterojunction Diode

Identifying defects/traps is of vital importance for the implementation of high-performance Ga2O3power devices. In this work, majority and minority carrier traps in beta-gallium oxide (β-Ga2O3) have been investigated and identified by means of deep level transient spectroscopy (DLTS) in Ni/β-Ga2O3Schottky barrier diode (SBD) and NiO/β-Ga2O3p+-n heterojunction diode (HJD). For both diodes, a dominant energy level of majority carrier (electron) trap states is determined to beEC-(0.75–0.79) eV with a concentration of (2.4–4.1)× 10^13cm^-3. Meanwhile, an additional trapping level atEV +0.14eV with a concentration of 1.2× 10^14cm^-3yield is present in NiO/β-Ga2O3bipolar HJD but absent in the Ni/β-Ga2O3SBD unipolar counterpart. The detection of such minority carrier traps originates from the hole injection through trap-assisted tunneling (TAT) fromp⁺-NiO toβ-Ga2O3. The bias- and frequency-dependent DLTS characteristics identify that such shallow-level minority carrier traps are located in theβ-Ga2O3bulk region rather not interfacial states at the NiO/β-Ga2O3heterointerface. The identification of both majority and minority carrier traps in this work may shed light on the in-depth understanding of carrier transport mechanisms in Ga2O3-based unipolar and bipolar power devices.