The etch rate and surface chemistry of AlxGa1minus;xAs after reactive ion etching (RIE) in CCl2F2:O2was examined as a function of etch time (1ndash;22 min), plasma power density (0.3ndash;1.3 Wthinsp;cmminus;2), pressure (1ndash;30 mTorr), gas composition (0percnt;ndash;80percnt; O2), gas flow rate (10ndash;50 sccm), sample temperature (50ndash;350thinsp;deg;C), and Al composition (x=0.15ndash;1). The etch rate is nonlinear with time, and decreases rapidly with increasing AlAs mole fraction. Essentially no temperature dependence of the etch rate is observed under our conditions, and there are no major differences in the surface chemistries of AlGaAs etched at different temperatures. The formation of a thin layer (50ndash;90 Aring;) of AlF3during the RIE treatment appears to control the etch rate, and the surface morphology becomes progressively smoother for increasing Al composition. No residual lattice disorder is detected by crosshyphen;sectional transmission electron microscopy under any of our conditions, although currenthyphen;voltage measurements on Schottky barrier diodes fabricated after RIE show higher ideality factors and barrier heights than unetched control samples. Annealing at 500thinsp;deg;C for 30 s almost restores the initial electrical properties of the material.
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