First-principles study of GaAs(001)-β2(2×4) surface oxidation and passivation with H, Cl, S, F, and GaO

Abstract

The interactions of oxygen atoms on the GaAs(001)-β2(2×4) surface and the passivation of oxidized GaAs(001)-β2(2×4) surface were studied by density functional theory. The results indicate that oxygen atoms adsorbed at back-bond sites satisfy the bond saturation conditions and do not induce surface gap states. However, due to the oxygen replacement of an As dimer atom at a trough site or row site, the As–As bond is broken, and gap states are produced leading to the Fermi level pinning because of unsaturated As dangling bonds. Atomic H, Cl, S, F, and the molecular species GaO were examined to passivate the unsaturated As dangling bond. The results show that H, Cl, F, and GaO can remove such gap states. It is also found that the interaction of S with the unsaturated As dangling bond does not remove the gap states, and new gap states are generated upon single S adsorption. A higher S coverage forms S–S dimer pairs which passivate two unsaturated As atoms, and removes the As-induced gap states.

High temperature GaAs X-ray detectors

“…Surface passivation of GaAs has been previously studied and shown to suppress, and even eliminate, the surface states, which are formed by segregated arsenic atoms via oxidation, giving rise to surface leakage current. [22][23][24] Both GaAs p þ -i-n þ diodes showed leakage current densities comparable with other high quality GaAs p þ -in þ diodes. Leakage current densities of 5.14 lA/cm 2 6 0.02 lA/cm 2 (for D1) and 1.937 lA/cm 2 6 0.008 lA/cm 2 (for D2) were recorded at the maximum investigated temperature (100 C) and internal electric field (50 kV/cm).…”

Symmetry Breaking-induced Band-splitting in GaAs Thin Film by First-principles Calculations

“…For instance, the low-temperature molecular beam epitaxy (MBE)-grown GaAs (LTGaAs), crucial to the development of terahertz emitter/detector 3,4) , with emerging applications in communications, imaging and sensing [5][6][7][8] , has its structural, electronic, and optical properties recently investigated theoretically [9][10][11][12] . In general, the GaAs(001) facet is considered due to the (2×4) or (4×4) reconstructions observed in the re‰ection high energy electron diŠraction (RHEED) and scanning tunneling microscopy (STM) [13][14][15] .…”

“…Other LT-GaAs systems are grown on (001) facets of Si or GaAs substrates, hence the prevalence of (001) facet [16][17][18] . The main outcome of the above theoretical works is the bandstructure or the density of states (DOS), which provide basis for further study of transport properties [9][10][11] . The methods employed are mainly density functional theory calculations using various potentials such as the pseudopotential 9) or projected augmented wave (PAW) method [10][11][12] .…”

“…The main outcome of the above theoretical works is the bandstructure or the density of states (DOS), which provide basis for further study of transport properties [9][10][11] . The methods employed are mainly density functional theory calculations using various potentials such as the pseudopotential 9) or projected augmented wave (PAW) method [10][11][12] . Many-body interaction is treated either within local density approximation (LDA) 9) , generalized-gradient approximation (GGA) 10,11) or Heyd-Scuseria-Ernzerhof (HSE) exchange-correlation functionals 12) .…”

“…The methods employed are mainly density functional theory calculations using various potentials such as the pseudopotential 9) or projected augmented wave (PAW) method [10][11][12] . Many-body interaction is treated either within local density approximation (LDA) 9) , generalized-gradient approximation (GGA) 10,11) or Heyd-Scuseria-Ernzerhof (HSE) exchange-correlation functionals 12) . The resulting degenerate electronic properties depending on the reconstructions or defects have been insightful [9][10][11][12] .…”