We report the molecular beam epitaxial growth of InGaP on GaAs (100) substrate
using a valved phosphorus cracker cell at
various substrate temperatures (Ts from
420 °C to 540 °C). Sample characterization was carried out using Raman scattering (RS),
photoluminescence (PL) and X-ray diffraction (XRD). Surface morphology
characterization was performed using scanning electron microscopy (SEM). Typical
InGaP layers showed a lattice mismatch of
< 10−3 and PL full-width at half maximum
(FWHM) of ~ 7 meV at 10 K.
The Raman spectrum showed peaks at 330 cm−1,
360 cm−1
and 380 cm−1
corresponding to the transverse-optic (TO), InP-like longitudinal-optic
(LO) and GaP-like LO modes, respectively. No Raman signals were detected
from the sample grown at substrate temperature
(Ts)
of 540 °C, due to poor surface
morphology arising
from indium desorption. A marginal increase in ordering, as
evidenced from the slight decrease (~ 30 meV) in the PL peak energy was seen in
samples grown at increasing substrate temperature. Furthermore, no significant
variation in the FWHM of the LO modes, TO mode and intensity ratio of the TO
mode to the InP-like LO mode were observed, suggesting that any ordering in the
material grown using this technique is weak.