Photoinduced current transient spectroscopy of deep levels and transport mechanisms in iron-doped GaN thin films grown by low pressure-metalorganic vapor phase epitaxy

Abstract

Laplace deep level transient spectroscopy of electron traps in epitaxial metalorganic chemical vapor deposition grown n-GaSb J. Appl. Phys. 113, 024505 (2013); 10.1063/1.4774100Effects of irradiation and annealing on deep levels in rhodium-doped p-GaAs grown by metal-organic chemicalvapor deposition Electrical transport and deep levels are investigated in GaN:Fe layers epitaxially grown on sapphire by low pressure metalorganic vapor phase epitaxy. Photoinduced current transient spectroscopy and current detected deep level spectroscopy are performed between 200 and 650 K on three Fe-doped samples and an undoped sample. A detailed study of the detected deep levels assigns dominant centers to a deep donor 1.39 eV below the conduction band edge E C and to a deep acceptor 0.75 eV above the valence band edge E V at low electric field. A strong Poole-Frenkel effect is evidenced for the donor. Schottky diodes characteristics and transport properties in the bulk GaN:Fe layer containing a homogenous concentration of 10 19 Fe/ cm 3 are typical of a compensated semiconductor. They both indicate that the bulk Fermi level is located typically 1.4 eV below E C , in agreement with the neutrality equation and dominance of the deep donor concentration. This set of results demonstrates unambiguously that electrical transport in GaN:Fe is governed by both types, either donor or acceptor, of the iron impurity, either substitutional in gallium sites or associated with other defects.

Electrical and optical properties of iron in GaN, AlN, and InN

“…Our results about the stability and electrical behavior of the Fe Ga -O N complex are in agreement with experimental observations by Muret et al [57]. Using deep-level optical spectroscopy (DLOS) studies on Fe-doped GaN grown by metallorganic vapor-phase epitaxy (MOVPE), they reported a donor level with an activation energy 1.39 eV below the GaN CBM [57].…”

Deep traps in GaN-based structures as affecting the performance of GaN devices

“…For example, the states at E c À1.35 eV and E v +0.8 eV in Ref. [177] are suspiciously close to the levels expected for C-related defects in low-pressure MOCVD GaN (see Section 3.4.1). For HVPE films in Ref.…”

“…For instance, in Ref. [177] the Fermi level in low-pressure MOCVD grown GaN:Fe films was reported to be pinned near E c À1.4 eV, with prominent electron traps at E c À1.35 eV and hole traps near E v +0.79 eV detected by PICTS.…”

Spinodal nanodecomposition in semiconductors doped with transition metals

“…Furthermore, the energetics of cubic and hexagonal (Ga,Mn)N arrangements has been studied with ab initio pseudopotential calculations and indeed δ doping has resulted likely to stabilize the zb phase (Choi et al, 2006). While extensive studies have been conducted on (Ga,Mn)N (Bonanni, 2007;Dietl, 2004;Graf et al, 2003;Liu et al, 2005;Pearton et al, 2003) as promising workbench for future applications in spintronics, until very re- cently, only little was known about (Ga,Fe)N. Formerly, and to a broad extent still now, this system is being widely considered as semi-insulating substrate for high frequency devices, as AlGaN/GaN high-mobility transistors (Heikman et al, 2003;Kashiwagi et al, 2007;Kubota et al, 2009;Lo et al, 2006;Muret et al, 2007). In this context and generally in relation to the use of this material system in reliable devices, careful studies of the electronic structure of (Ga,Fe)N have been carried out and especially the knowledge of the exact position of the Fe 3+/2+ acceptor level within the band gap-used to predict band offsets in heterostructures on the basis of the internal reference rule (Langer and Heinrich, 1985)-has been considered of great importance.…”