V III RATIO EFFECTS ON THE GROWTH OF IN1-X-YGAXALYAS ON INP SUBSTRATES BY MOLECULAR-BEAM EPITAXY/

In this paper, we report the effects of arsenic pressure (V/III ratio) on the properties of undoped In1-x-yGaxAlyAs layers grown by molecula r beam epitaxy (MBE) on InP (100) substrates. The quaternary samples w ere analysed using double-axis X-ray diffraction (XRD) and low-tempera ture photoluminescence (PL). XRD analysis showed that the lattice mism atch was relatively insensitive to flux ratio variations within the ra nge investigated (V/III from 14 to 73). PL full width at half-maximum (FWHM) as low as 12.7 meV (at 5 K), a value which is comparable to the best reported, was achieved at a V/III ratio = 33. The PL and XRD FWH Ms broadened significantly as the V/III ratio was decreased below 21 o r increased above 50. Within the range investigated, the optimum V/III ratio for the growth of InGaAlAs layers was found to be 21-50. The ef fect of the V/III ratio on the optical and crystalline properties was explained in terms of clustering, which was characterized by analysing the difference between the PL peak energy and the band-gap energy cal culated from XRD compositional measurements. (C) 1998 Published by Els evier Science Ltd. All rights reserved.