Observation of weak ordering effects and surface morphology study of InGaP grown by solid source molecular beam epitaxy

• Published in: Microelectronics 2000-01, Vol.31 (1), p.15-21
• Main Authors: Yoon, S.F., Mah, K.W., Zheng, H.Q., Gay, B.P., Zhang, P.H.
• Format: Article
• Language: English
• Subjects: InGaP samples; Raman scattering measurement; Solid source molecular beam epitaxy (SSMBE)
• ISSN: 1879-2391; 0026-2692; 1879-2391
• DOI: 10.1016/S0026-2692(99)00085-3

We report the characterization of InGaP grown lattice-matched to GaAs using a valved phosphorus cracker cell in solid source molecular beam epitaxy (SSMBE) over a wide range of substrate temperature (Ts from 420 to 540°C). The optical bandgap and lattice-mismatch were determined using low temperature photoluminescence (PL) and X-ray diffraction (XRD). Raman scattering measurements showed signals at 330, 360 and 380cm−1 which correspond to the InP-like transverse-optic (TO), InP-like longitudinal-optic (InP-LO) and GaP-like LO modes, respectively. The sample grown at Ts=540°C showed poor surface morphology caused by indium desorption as verified by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) examination. The optical bandgap decreased marginally (∽23meV) while the ordering parameter increased slightly in samples grown at an increasing substrate temperature. The relatively small variation in the Raman intensity of the InP-like and GaP-like LO mode and the marginal decrease in the valley-to-peak intensity ratio of the InP-like LO mode indicate the presence of relatively weak ordering effects in the material. Further evidence of weak Cu–Pt-type ordering comes from the observation of a signal at 354cm−1 in the Raman spectrum.