THE EFFECT OF ELASTIC STRAIN ON THE OPTICAL-PROPERTIES OF INGAP GAAS GROWN USING A VALVED PHOSPHORUS CRACKER CELL IN SOLID SOURCE MBE/

We report the effect of elastic strain on the optical properties of In 1-xGaxP grown using a valved phosphorus cracker cell in solid source m olecular beam epitaxy (SSMBE). Sample characterization was carried out using photoluminescence (PL) and double-axis X-ray diffraction (XRD). All the In1-xGaxP epilayers prepared in this study are gallium-rich ( tensile strained) with composition x in the range of 0.516<x<0.559. Th e unstrained plot of the band-gap as a function of composition x was d educed from the tensile-strained data obtained experimentally by assum ing that the valence band splitting is due only to biaxial elastic str ain. The unstrained plot of band-gap vs. composition x for our MBE-gro wn samples was about 10 meV and 20 meV lower than those reported for s amples grown by organometallic vapour phase epitaxy (OMVPE) and Liquid phase epitaxy (LPE) techniques, respectively. The photoluminescence ( PL) full width at half-maximum (FWHM) of the InGaP samples was higher as the composition x increases due to an increase in the lattice misma tch. Compared to other growth techniques involving the use of higher s ubstrate temperature, InGaP of comparable optical quality can be grown using the valved phosphorus cracker cell SSMBE technique. (C) 1998 El sevier Science S.A. All rights reserved.