Annealing-induced-type conversion of GaInNAs

When grown by metalorganic chemical vapor deposition (MOCVD), nominally undoped GaInNAs is commonly observed to have an acceptor concentration of ∼1017 cm−3. However, after annealing in the MOCVD reactor at a temperature of 650 °C, p-type GaInNAs sometimes converts to n type with an electron concentration of ∼1017 cm−3. This n-type material has a slightly higher electron mobility (∼400–450 cm2/V s) than has usually been reported for 1 eV GaInNAs. Secondary ion mass spectroscopy shows significant hydrogen and some carbon contamination of these layers. The type conversion is correlated with both the nitrogen and hydrogen concentration and is relatively insensitive to the choice of growth precursors (trimethylgallium versus triethylgallium, or unsymmetric dimethylhydrazine versus nitrogen trifluoride). The data are consistent with theoretical predictions that the donors arise from a N–H complex. Annealing in the absence of hydrogen reduces the background acceptor concentration, but does not produce an electron concentration as high as 1017 cm−3.