Influence of Ga precursor choice on ordering degree of MOVPE grown Ga 0.5In 0.5P

Abstract

The degree of ordering of MOVPE grown InGaP is determined as a function of growth temperature ( T g) using two different gallium precursors: trimethylgallium (TMGa) or triethylgallium (TEGa). We measured the band gap, which is directly related to the degree of ordering, with low-temperature photoluminescence (PL). For InGaP grown with TMGa, the band gap was lowest for layers grown at T g=640°C (1.89 eV; highest degree of ordering), whereas a higher band gap and thus a lower degree of ordering was measured for layers grown at T g=600, 720 or 760°C. The difference between the highest and lowest measured band gap was 44 meV. For the layers grown with TEGa this difference was only 15 meV and the band gap at all growth temperatures exceeded 1.925 eV at 4.2 K, which is indicative of a fairly low degree of ordering. So, growth of InGaP on GaAs using TEGa instead of TMGa as the gallium precursor produces a lower degree of ordering which is independent of the growth temperature.