【International Papers】Deep Level Traps in (010) β-Ga₂O₃ Epilayers Grown by Metal Organic Chemical Vapor Deposition on Sn-Doped β-Ga₂O₃ Substrates

      Researchers from the The University of Manchester have published a dissertation titled "Deep level traps in (010) β-Ga₂O₃ epilayers grown by metal organic chemical vapor deposition on Sn-doped β-Ga₂O₃ substrates " in Journal of Applied Physics.

ABSTRACT

      In this work, conventional deep-level transient spectroscopy (DLTS) and high-resolution Laplace-DLTS (L-DLTS) have been used to characterize deep-level traps in (010) β-Ga₂O₃ epilayers grown by metal organic chemical vapor deposition on native Sn-doped substrates. Two types of epilayers have been studied, one doped with silicon during growth to about 1.5 × 10¹⁷ cm⁻³ and the other type was unintentionally doped (UID). Electrical measurements were conducted on Au and Pt Schottky barrier diodes. In the Si-doped samples, only one electron trap with emission activation energy of 0.42 eV (E_0.42) and concentration of (6–8) × 10¹³ cm⁻³ has been detected. In the UID samples, in addition to the E_0.42 trap, two other traps with activation energies for electron emission of 0.10 eV (E_0.10) and 0.53 eV (E_0.53) have been observed. Dependencies of electron emission rate (e_em) on the electric field (E) as well as concentration-depth profiles {N_T(W)} have been measured and analyzed for the E_0.10 and E_0.42 traps. The eem(E) dependence for the E_0.10 trap is characteristic for a donor energy level, while that for the E_0.42 trap indicates an acceptor level. The N_T(W) dependencies show non-uniform spatial distributions of both the E_0.10 and E_0.42 traps in the UID samples, with the concentration of the E_0.10 trap dropping from about 1 × 10¹⁵ cm⁻³ at 1.5 μm from the surface to about 2 × 10¹³ cm⁻³ at 0.5 μm, which indicates out-diffusion from the substrate or interface into the epilayer as a likely source. The results obtained are compared with the literature, and possible origins of the detected traps are discussed.

FIG. 1. Current density–voltage (J–V) dependencies for the Au Schottky diodes on the Si-doped (red curve) and the UID (blue curve) epilayers, measured at 295 K.

FIG. 2. (a) 1/Cb² dependencies on the applied reverse bias and (b) spatial profile of the uncompensated donors [N_d (W)] for the Au Schottky diodes on the Si-doped (red curves) and UID (blue curves) epilayers. Results are derived from capacitance–voltage (C–V) measurements conducted at 295 K.

DOI：

https://doi.org/10.1063/5.0202581