In situ time-resolved monitoring of PH3 induced exchange reactions on GaAs under metalorganic vapor phase epitaxy conditions

Abstract

Exposure of GaAs and InGaAs to PH3 is a standard step in gas switching sequences for metalorganic vapor phase epitaxy (MOVPE) growth of heterostructures in the technologically important GaAsP, InGaP, and InGaAsP material systems. The exchange of group-V atoms was monitored in situ by reflectance anisotropy spectroscopy when GaAs is exposed to PH3. The c(4×4) reconstructed, As-terminated GaAs surface is then replaced by a P-terminated structure. At standard MOVPE growth temperatures and pressures the time constant for this reaction is of the order of 100 ms. The temperature and pressure dependence of the As by P exchange is reported, and the activation energy was determined to be 1.64 eV. It is concluded that PH3 enhances the desorption of As.

Growth monitoring of GaAsSb:C/InP heterostructures with reflectance anisotropy spectroscopy

“…Also, different bond strengths of Ga-Sb and In-Sb would influence the surface processes that have been investigated. Similar in situ studies of exchange reactions of As by P on GaAs and P by As on InP were done by Jo¨nsson et al [14] and Zorn [15], respectively. The calculated activation energies were 0.8 eV for the P-As exchange reaction and 1.64 eV for the As-P exchange by exposing GaAs to PH 3 .…”

Application of reflectance anisotropy spectroscopy to laser diode growth in MOVPE

“…This test sample contains three GaAs y P 1Ày QWs with different compositions, y resulting in different emission wavelengths. A strong dependence of the RA signal on GaAsP composition grown on GaAs is reported in the literature [14,15] for photon energies around 2.5 and 3.8 eV at growth temperature, respectively. Taking into account the reduced penetration depth with increasing photon energy the growth of the QWs was monitored here at 3.8 eV (326 nm).…”

AlGaAs/InGaP interfaces in structures prepared by MOVPE

“…An impact of the As/P exchange process on the InGaPon-AlGaAs interface in sample #803 can be characterized by the formation of an AlGaP or AlGaPAs wide band gap interlayers. A time constant of 0.5 s can be extrapolated for the As/P exchange process at 560 1C from data published in [24]. Therefore, one can expect: (1) the formation of an AlGaP monolayer with top As atoms nearly completely exchanged with P atoms; and (2) the formation of an underlying graded AlGaPAs interlayer as a consequence of diffusion during the 5 s phosphine pre-flow.…”