Wet oxidation of AlxGa1−xAs: Temporal evolution of composition and microstructure and the implications for metal-insulator-semiconductor applications

Ashby, Carol I. H.; Sullivan, John P.; Newcomer, P.P.; Missert, Nancy A.; Hou, H.Q.; Hammons, B. E.; Hafich, M. J.; Baca, Albert G.

doi:10.1063/1.118897

Cited by 54 publications

(34 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although recent research has cast doubts on the feasibility of using this oxide for a metaloxide-semiconductor ͑MOS͒-type device, 2 it has found wide usage in the creation of vertical-cavity surface-emitting lasers ͑VCSELs͒. The oxide provides both current confinement and index guiding, producing the lowest threshold 3 and highest efficiency 4 VSCELs ever reported.…”

Section: Introductionmentioning

confidence: 99%

Effect of cylindrical geometry on the wet thermal oxidation of AlAs

Alonzo

Cheng

McGill

1998

Journal of Applied Physics

View full text Add to dashboard Cite

We have investigated the wet thermal oxidation of AlAs in cylindrical geometry, a typical configuration for vertical-cavity surface-emitting lasers. Through both experiment and theoretical calculations, we demonstrate a significantly different time dependence for circular mesas from what has been reported in the literature both in studies of stripes and in a study of circular mesas. We attribute this different time dependence to the effect of geometry on the oxidation.

show abstract

Section: Introductionmentioning

confidence: 99%

Effect of cylindrical geometry on the wet thermal oxidation of AlAs

Alonzo

Cheng

McGill

1998

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…8 These traps lead to increased interface recombination velocity 9,10 and high leakage currents. 11 However, the wet thermal oxides of As-free In 0.485 Al 0.515 P (lattice matched to GaAs) have been found to possess excellent insulating 12,13 and interfacial properties 13,14 and may provide a viable native oxide for III-V MOS devices.…”

mentioning

confidence: 99%

Electrical properties of InAlP native oxides for metal–oxide–semiconductor device applications

Cao

Zhang

et al. 2005

Applied Physics Letters

View full text Add to dashboard Cite

Data are presented on the insulating properties and capacitance-voltage (CV) characteristics of metal-oxide-semiconductor (MOS) device-thickness (below ~100 nm) native oxides formed by wet thermal oxidation of thin InAlP epilayers lattice matched to GaAs. Low leakage current densities of J=1.4 x 10 -9 A/cm 2 and J=8.7 x 10 -11 A/cm 2 are observed at an applied field of 1 MV/cm for MOS capacitors fabricated with 17 nm and 48 nm oxides, respectively. TEM images show that the In-rich interfacial particles which exist in 110 nm oxides are absent in 17 nm oxide films. Quasi-static capacitance-voltage measurements of MOS capacitors fabricated on both n-type and p-type GaAs show that the InAlP oxide-GaAs interface is sufficiently free of traps to 1 support inversion, indicating an unpinned Fermi level. These data suggest that InAlP native oxides may be a viable insulator for GaAs MOS device applications. 2Due to the wide array of high electron mobility alloys of varying bandgaps that can be epitaxially grown on its surface, GaAs remains the most widely used semiconductor for high-speed electronic applications. While Schottky gates are commonly used in high-speed GaAs transistors, the restricted forward bias (a few tenths of a volt) that can be applied without excessive gate leakage currents limits their power handling capability.The electrical characteristics of native oxides of GaAs are far inferior to those of SiO 2 on Si, and an alternative insulator has long been pursued 1,2 to enable the preferred metal-insulator-semiconductor gate structure. Many deposited insulator/GaAs structures have been investigated, although only a few have yielded promising results. 3-6 Native oxide films on GaAs can offer advantages of processing convenience and low cost.Wet thermal oxides of AlGaAs 7 have been studied but found to suffer from midgap traps caused by residual interfacial As. 8 These traps lead to increased interface recombination velocity 9,10 and high leakage currents. 11 However, the wet thermal oxides of As-free As shown in the bright-field TEM images of Fig. 2, dark particles exist near the oxide/GaAs interface in the 110 nm oxide of Fig. 2 (a), while no dark interfacial particles appear in the 17 nm oxide of Fig. 2 (b). Fig. 2 (b) is representative of the entire observable area for this and a second wedge-polished cross section specimen, with the absence of particles also confirmed for plan-view specimens (not shown) in which possible loss of particles due to ion milling and electron beam interactions is suppressed by the fact that they are protected from the vacuum by the substrate and overlying oxide film. The interfacial particles in Fig. 2 (a) are believed to be indium rich based on Z-contrast TEM images 16 (not shown) and Auger depth profiling. 17 The size of the particles increases with the progressive consumption of the InAlP epilayer during oxidation. 16 We hypothesize that In, the heaviest element in the structure, outdiffuses more slowly than the other alloy constituents and hence accumulates near the inter...

show abstract

“…It is well known that the interface between GaAs and aluminum oxide (AlO x ), produced by wet oxidation of AlAs, provides a very high density of charge traps, in the form of amorphous oxide and microcrystallites [23], and in the form of elemental interfacial As [24], leading to spatially nonuniform Fermi level pinning [25]. The time-resolved charge decay measurements presented below confirm that the charges are relatively long lived on a ∼10 ms time scale.…”

mentioning

confidence: 51%

Quantum dot nonlinearity through cavity-enhanced feedback with a charge memory

et al. 2015

View full text Add to dashboard Cite

In an oxide apertured quantum dot (QD) micropillar cavity-QED system, we observe strong QD hysteresis effects and line-shape modifications even at very low intensities corresponding to <10 −3 intracavity photons. We attribute this to the excitation of charges by the intracavity field; they get trapped at the oxide aperture, where they screen the internal electric field and blueshift the QD transition. This in turn strongly modulates light absorption by cavity-QED effects, eventually leading to the observed hysteresis and line-shape modifications. The cavity also enables us to observe the QD dynamics in real time, and all experimental data agree well with a power-law charging model. The observed charging effect can serve as a tuning mechanism for quantum dots. [6][7][8], and hybrid quantum information schemes [9,10]. However, QDs deviate from ideal atomlike systems as they strongly interact with their environment, for example, through nuclear spins [11,12] and via charge traps [13,14]. These interactions need to be understood and controlled in order to improve the QD coherence properties. For this purpose, cavities are very useful to probe the QD environment, through increased light-matter interactions.In this Rapid Communication we investigate such a QDcavity system. For a sufficiently low optical field intensity this system can be described by the QED of an effective two-level system in a single-mode cavity. For increasing intensities we report on bistable and strong nonlinear behavior. The sample under study consists of InAs self-assembled QDs inside a p-i-n diode structure embedded in a micropillar cavity. This system combines QD charge and Stark shift control by applying a bias voltage with high-quality polarization-degenerate cavity modes [15][16][17][18][19]. The mode confinement in the transversal direction is achieved by an oxide aperture formed through a wet oxidation step. The observed bistability and nonlinear behavior in the cavity-QED system can be explained by attributing a second role to the oxide aperture, namely, that of a charge memory. Charges in this memory, created by resonant absorption, will cause a modification of the internal electric field which shifts the QD frequency, and this in turn modifies the amount of absorption. In Fig. 1(a) the sample structure, with charges trapped at the oxide aperture, is schematically shown.We consider one of the fine-split transitions of a charge neutral QD coupled to a polarization-degenerate cavity mode in the intermediate coupling regime. Figure 1(b) shows reflection spectra, recorded at a sufficiently low incident intensity P in = 1 pW such that no nonlinear effects occur. Upward and downward frequency scans overlap perfectly and can be fitted by theory for a dipole inside an optical cavity, which we will discuss later in detail. However, when a higher intensity of 1 nW is used, several strong deviations occur [see Fig. 1(c)]. First of all, a hysteresis feature appears when the QD is tuned at or below the cavity resonance. Second, while at the high f...

show abstract

Wet oxidation of AlxGa1−xAs: Temporal evolution of composition and microstructure and the implications for metal-insulator-semiconductor applications

Cited by 54 publications

References 8 publications

Effect of cylindrical geometry on the wet thermal oxidation of AlAs

Effect of cylindrical geometry on the wet thermal oxidation of AlAs

Electrical properties of InAlP native oxides for metal–oxide–semiconductor device applications

Quantum dot nonlinearity through cavity-enhanced feedback with a charge memory

Contact Info

Product

Resources

About