Growth of high-quality InGaP on GaAs by gas-source molecular beam epitaxy using tertiarybutylphosphine

In_0.48Ga_0.52P lattice matched to GaAs is becoming increasingly important as a material for photonic and electronic devices. Gas-source molecular beam epitaxial growth (GSMBE) using tertiarybutylphosphine (TBP) is an attractive growth method of InGaP combining the monolayer level growth control capability of MBE with the low toxic nature of TBP. However, the electronic and optical properties of InGaP epitaxial layers grown by GSMBE using TBP have so far been inferior to those by GSMBE using PH₃, and those by MOCVD, and sometimes GSMBE results in highly compensated undoped high-resistive layers. The purpose of this paper is to demonstrate that In_0.48Ga_0.52P layers having electronic and optical properties comparable to the best data reported for MOCVD can be grown by GSMBE using TBP, if the growth conditions are systematically optimized. Optimization of the growth conditions was made based on RHEED observations. The 77 K photoluminescence (PL) spectrum of In_0.48 Ga_0.52P layers was dominated by a peak due to a InGaP band-edge emission at 1.96 eV with a narrow line width (FWHM) of 15.5 meV. The undoped InGaP layers grown under the optimum growth condition showed high electron mobility values and low carrier concentrations. The highest electron mobility at 300 K was 3300 cm²/V.s and that at 77 K was 21000 cm²/V.s at the carrier concentration value of n=5×10¹⁴-1×10¹⁵ cm³. These data are compared with the best values reported so far for various growth methods