Evolution of conduction and interface states of laterally wet-oxidized AlGaAs with oxidation time

Abstract

The conduction and interface states of laterally wet-oxidized GaAs-AlGaAs-GaAs structures after various oxidation times are investigated. Effective current blocking is achieved after 150min oxidation and the conduction of current through the oxidized AlGaAs layer is controlled by the Poole-Frenkel mechanism, from which a relative dielectric constant of 7.07 is obtained. At an oxidation time of 15min, capacitance-voltage spectra exhibit capacitance dispersion over frequency, implying the presence of an interface state. The intensity of the dispersion increases with increasing the oxidation time and admittance spectroscopy reveals a significant interface state at ∼0.28eV at 45min. Further increasing the oxidation time to 150min broadens the interface state to a set of continuous interface states from 0.19–0.31eV with decreasing densities from 3×1011to0.9×1011eV−1cm−2 and generates fixed charges of about 9.1×1011cm−2 in the oxidized layer. By comparison to a similar trap in a relaxed InGaAs∕GaAs, the interface state is tentatively assigned to the interaction of residual As with dislocations.

Three dimensional confinement technology based on buried patterned AlOx layers: Potentials and applications for VCSEL arrays

“…In the area at the vicinity of the holes, the photoluminescence intensity is five times greater in the apertures between the oxidation fronts than in the fully oxidized zones. This may be due to the presence in the oxide zone of GaAs / AlOx interfaces that promotes non-radiative recombination which reduces the PL emission in this interfacial region [6][7][8]. Indeed, we observed the same result for structures where the oxide was formed after the epitaxy of the entire structure with a surface layer of 200 nm (standard lateral oxidation process).…”

Toward an AlGaAs/AlOx near-infrared integrated optical parametric oscillator

“…Since Al 2 O 3 and GaAs themselves are known to be transparent in the near IR [26,27], we tentatively ascribe these additional losses to point defects associated to energy levels in the semiconductor gap, and created during the oxidation process in the GaAs layers adjacent to AlOx. Arsenic antisites (As Ga ) in particular have already been supposed to introduce donor levels with similar properties in the gap of AlGaAs, in optical devices [28] as well as in electrical devices [29]. Such defects may arise from trapped oxidation reaction products resulting in an excess of elemental arsenic As 0 at the oxide-semiconductor interfaces.…”

Near-infrared OPO in an AlGaAs/AlOx waveguide

“…Since Al 2 O 3 and GaAs themselves are known to be transparent in the near IR, we tentatively ascribe these additional losses to point defects associated to energy levels in the semiconductor gap and created during the oxidation process in the GaAs layers adjacent to AlOx. Arsenic antisites (As Ga ) have already been supposed to introduce donor levels with similar properties in the gap of AlGaAs, in optical devices [28] as well as in electrical devices [29]. Such defects might arise from trapped oxidation reaction products resulting in an excess of elemental arsenic As 0 at the oxide-semiconductor interfaces.…”