A study of deep levels in vanadium-doped GaAs grown by OMVPE

Abstract

Vanadium(V)-doped GaAs layers grown by metal organic vapour phase epitaxy using vanadium tetrachloride as a doping source were characterized by deep level transient spectroscopy. The only deep level detected in undoped GaAs is EL2. After V doping, the EL2 defect was not detected. This observation is explained by a reaction involving V and the EL2 arsenic antisite. V doping creates an electron trap (E1) at 0.14 eV below the conduction band, associated with the transition V 3+ /V 2+ , and a broad band (E2) of electron traps. The E1 concentration increases with increasing V doping to reach a maximum value of 10 16 cm −3 for a total V concentration of about 10 18 cm −3 . The E2 band is characterized by a defect distribution similar to the so-called U band. We propose that it is associated with intrinsic defects introduced by the growth conditions.

Growth of vanadium-doped GaN by MOVPE

“…3). This is comparable to the variation of V incorporation GaAs, where a is about 1.9 [21]. The increase of the V background level along the growth direction indicated some reactor memory effect.…”

Diffusion of vanadium in GaAs

“…In Ref. [16], we have shown that V incorporates in Ga sites, which causes reduction in Ga vacancy density.…”

“…The growth procedure, electrical and optical properties of the grown layers are described in Refs. [13][14][15][16].…”

Effects of thermal annealing onn-type GaAs:V grown by MOCVD

“…Figure 1 shows the room temperature Hall carrier concentration for samples which were as-grown and annealed at 750 • C. The data for the as-grown GaAs:V have already been published [17] but are reproduced here for the sake of completeness. The V where α is about 1.9 (figure 1 in [18]). After annealing at 750 • C, two domains are clearly observed.…”

“…V doping creates an electron trap E1 at 0.14 eV below the conduction band, associated with the transition V 3+ /V 2+ . The DLTS spectra of the as-grown Vdoped layers are described in detail in [18]. After annealing we noted the appearance of the E3 trap.…”