Experimental exploration of the amphoteric defect model by cryogenic ion irradiation of a range of wide band gap oxide materials

Abstract

The evolution of electrical resistance as function of defect concentration is examined for the unipolar n-conducting oxides CdO, β-Ga 2 O 3 , In 2 O 3 , SnO 2 and ZnO in order to explore the predictions of the amphoteric defect model. Intrinsic defects are introduced by ion irradiation at cryogenic temperatures, and the resistance is measured in-situ by current-voltage sweeps as a function of irradiation dose. Temperature dependent Hall effect measurements are performed to determine the carrier concentration and mobility of the samples before and after irradiation. After the ultimate irradiation step, the Ga 2 O 3 and SnO 2 samples have both turned highly resistive. In contrast, the In 2 O 3 and ZnO samples are ultimately found to be less resistive than prior to irradiation, however, they both show an increased resistance at intermediate doses.Based on thermodynamic defect charge state transitions computed by hybrid density functional theory, a model expanding on the current amphoteric defect model is proposed.

Doping limitation due to self-compensation by native defects in In-doped rocksalt Cd x Zn1−x O

“…When E F is above (below) E FS the formation energy of acceptor (donor) type native defects is lower and the formation of acceptor (donor) is energetically favorable so as to pull the E F of the material toward E FS . The ADM has been applied to successfully explain doping/compensation mechanisms in many semiconductors including TCO materials such as SnO 2 , In 2 O 3 and CdO [25][26][27]. In the case of CdO, due to the low position of the CBM, E FS is at ∼1 eV above CBM [28,29], which corresponds to an n ∼ 5 × 10 20 cm −3 .…”

Fermi level controlled point defect balance in ion irradiated indium oxide

“…1 may be readily proposed. 11 Importantly, by comparing samples exhibiting different E F -values selected for the present study, we go beyond such qualitative analysis and unveil interesting correlations. Guided by theory, 12 we illustrate our analysis for the defect accumulation in the low-dose regime by Fig.…”

“…9 In this context, in situ resistance measurements as a function of the irradiation dose have recently unveiled interesting correlations in oxide semiconductors. 10,11 However, even though Refs. 10 and 11 have investigated a range of different materials (ZnO, CdO, SnO 2 , Ga 2 O 3 and In 2 O 3 ), a direct unambiguous demonstration of the dynamic E F -control over the point defect balance is missing.…”

15 MeV proton damage in NiO/β-Ga2O3vertical rectifiers

“…While the Ga 2 O 3 is known to be relatively resistant to total dose damage [27,28], large reversible changes in current-voltage characteristics of the heterojunctions have been observed after Co-60 gamma ray exposure which appears to be due to conductivity changes in the NiO [29]. Other low dose ion irradiated oxides have also shown enhanced conductivity which in some cases has been linked to irradiation/illumination assisted desorption of oxygen containing species from the oxide surface [30][31][32][33]. There have also been recent demonstrations of single event burnout (SEB) in Ga 2 O 3 rectifiers [34], while simulations show the SEB threshold voltage of conventional Ga 2 O 3 MOSFETs is lower than that of state-of-the-art AlGaN/GaN HEMTs [35,36].…”