Characterization of InP grown by OMVPE using trimethylindium and tertiarybutylphosphine (TBP) at low V/III ratios and reduced TBP partial pressures

Abstract

We report an OMVPE growth process for InP using trimethylindium (TMI) and tertiarybutylphosphine (TBP), a V/III ratio of 15, and a TBP partial pressure of 0.5 Torr. Growth is initiated with a 0.1 μm buffer layer employing a ramped TBP flow. Results are presented for InP grown with two different samples of both TMI and TBP and compared to previous experimental results and theoretical predictions. Good surface morphology is obtained from 540 to 600° C. The net carrier concentrations, Nd-Na, decrease with increasing growth temperature—but never fall below 1.3 × 1016 cm-3. Mobilities of 3990 and 11200 cm2/V.sec are observed at 300 and 77 K, respectively. At 77 K, we infer a compensation ratio of ∼0.4, independent of Nd-Na. Photoluminescence measurements at 6 K show intense near bandgap emission with a full width half maximum proportional to Nd-Na. Weak emission is also observed from carbon acceptors, independent of growth temperature. Secondary ion mass spectroscopy measurements are performed on an InP wafer grown with four different temperatures. The observed sulfur concentration drops from 1 × 1018 to 6 × 1016 cm-3 with increasing growth temperature. This confirms that sulfur is an important residual impurity in TBP. The observed carbon concentration is 4–6 × 1016 cm-3, regardless of growth temperature.