Pulsed anodic oxidation of GaAs for impurity-free interdiffusion of GaAs/AlGaAs quantum wells

Deenapanray, Prakash; Fu, Lan; Petravić, M.; Jagadish, Chennupati; Gong, Bin; Lamb, Robert N.

doi:10.1002/1096-9918(200011)29:11<754::aid-sia924>3.0.co;2-d

Cited by 3 publications

(4 citation statements)

References 23 publications

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“…28 In this case, defects are created by the metallurgical reaction between the native oxide layer and GaAs. 12,21 We have shown that the single donor state ͑0/ϩ͒ of EL2 in disordered n-type GaAs exhibits a depth profile that decays exponentially below the surface. 27 Figure 4a reveals that the depth profile of HC2 shows a conspicuous decrease toward the surface.…”

Section: Resultsmentioning

confidence: 97%

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Electrical Characterization of Impurity-Free Disordered p-Type GaAs

Deenapanray¹,

Coleman²,

Jagadish³

2003

Electrochem. Solid-State Lett.

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Impurity-free disordered p-GaAs epi layers by SiO 2 or native oxide capping are characterized using deep level transient spectroscopy ͑DLTS͒ and capacitance-voltage measurements. Samples, including an uncapped epi layer for reference, were annealed at 900°C for 30 s under Ar ambient. Disordering resulted in an increase in the free hole concentration with the effect being more pronounced for the SiO 2 capping layer. DLTS measurements revealed the corresponding increase in the concentrations of both the Cu and Zn-related deep levels in the disordered epi layers. We relate these changes in electrical properties to segregation effects resulting from the nonequilibrium injection of excess gallium vacancies in the disordered p-type epi layers. We discuss the relative merit of using either SiO 2 or native oxide layers for the integration of optoelectronic devices.

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Section: Resultsmentioning

confidence: 97%

“…Details of our electrochemical cell have been described elsewhere. 21 Thin native oxide layers ͑30 nm͒ have recently been used successfully to engineer the bandgap of GaAs-based laser diodes for the fabrication of multiwavelength lasers by the IFD process. 22 Another set of samples was capped with 30 nm SiO 2 by plasma-enhanced chemical vapor deposition.…”

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confidence: 99%

Electrical Characterization of Impurity-Free Disordered p-Type GaAs

Deenapanray¹,

Coleman²,

Jagadish³

2003

Electrochem. Solid-State Lett.

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“…12 More recently, pulse anodic oxidation with constant voltage sources have been used to grow native oxides for III-V semiconductor device fabrication. [13][14][15][16][17] Pulsed anodization produces uniform oxides at growth rates 10 times faster than anodization with constant voltage sources at room temperature. 14 AlGaAs diode lasers fabricated with pulsed anodic oxides had threshold currents substantially lower than lasers fabricated with SiO 2 .…”

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confidence: 99%

“…13 Pulsed anodization of GaAs has successfully been used to achieve impurity-free interdiffusion of GaAs/AlGaAs quantum wells. [15][16][17] Moreover, oxides formed on (AlGa) 0.5 In 0.5 P have been shown to emit visible light during pulsed anodic oxidation. 14 Despite the promising use of the pulsed anodic technique for optoelectronic devices fabrication, little is known about the properties of pulsed anodic oxides, especially those formed on InP.…”

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On the Pulsed Anodic Oxidation of n[sup +]-InP

Deenapanray

Martin

Lever

et al. 2002

Electrochem. Solid-State Lett.

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We have performed a parametric investigation of the anodic oxidation of highly doped n-type InP͑100͒ using a pulsed current source. Approximately 75% of the oxide growth took place within the first ϳ10 s of oxidation, and the equilibrium oxide thickness was reached soon thereafter. The oxide thickness, d ox , varied linearly with potential difference between electrodes, V, with d ox Ӎ 1 nm/V. This value could be as high as ϳ1.85 nm/V when optimum conditions are used for anodization. We have also correlated d ox with the maximum current density, J max , and observed an exponential dependence. Furthermore, d ox increased slowly with the increasing duty cycle, , of the pulse train and reached a maximum for ϭ 4/6. Highly symmetrical structures consisting of pyramid-shaped protrusions located at the center of circular walls were observed on oxidized surfaces by atomic force microspcopy. To the best of our knowledge, this is the first report of such topographical features on electrochemically oxidized InP surfaces.

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Defect Engineering and Atomic Relocation Processes in Impurity-Free Disordered GaAs and AlGaAs

et al. 2003

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Impurity-free disordering (IFD) of GaAs and AlxGa1-xAs epitaxial layers using SiOx capping in conjunction with annealing was studied by deep level transient spectroscopy (DLTS) and capacitance-voltage (C-V) measurements. Three dominant electron traps S1 (EC– 0.23 eV), S2* (EC– 0.53 eV), and S4 (EC– 0.74 eV) are created in disordered n-type GaAs. The electron emission rate of S1 is enhanced in the presence of an externally applied electric field. We propose that S1 is a defect that may involve As-clustering or a complex of arsenic interstitials, Asi, and the arsenic-antisite, AsGa. S2* is shown to be the superposition of two defects, which may be VGa-related. S4 is identified as the defect EL2. Our preliminary results indicate that the same set of defects is created in disordered n-type AlxGa1-xAs, with S1 pinned to the conduction band edge, while S2* and S4 are pinned relative to the Fermi level. In contrast to disordering in n-type GaAs, IFD of p-type GaAs results in the pronounced increase in the free carrier concentration in the near-surface region of the disordered layer. Two electrically active defects HA (EV+ 0.39 eV) and HB2 (EV+ 0.54 eV), which we have attributed to Cu- and Asi/AsGa-related levels, respectively, are also observed in the disordered p-GaAs layers. IFD causes segregation of Zn dopant atoms and Cu towards the surface of IFD samples. This atomic relocation process poses serious limitations regarding the application of IFD to the band gap engineering of doped GaAs-based heterostructures.

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Pulsed anodic oxidation of GaAs for impurity-free interdiffusion of GaAs/AlGaAs quantum wells

Cited by 3 publications

References 23 publications

Electrical Characterization of Impurity-Free Disordered p-Type GaAs

Electrical Characterization of Impurity-Free Disordered p-Type GaAs

On the Pulsed Anodic Oxidation of n[sup +]-InP

Defect Engineering and Atomic Relocation Processes in Impurity-Free Disordered GaAs and AlGaAs

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