Calibration of SIMS measurements of unintentional oxygen concentrations in Al0.3Ga0.7NyAs(1-y) and assessment of the purity of 1,1-dimethylhydrazine

There is significant commercial interest in 1.3 μm dilute nitride-based laser devices. Such devices rely on low concentrations of nonradiative centres in the active region in order to achieve the predicted high performances. Unintentional oxygen contamination in alkyl precursors used in the epitaxy is a source of nonradiative centres. An investigation of the Secondary Ion Mass Spectrometry (SIMS) relative sensitivity factor (RSF) for oxygen in Al_0.3Ga_0.7N_yAs_(1-y) was made in order to calibrate and compare background oxygen impurities in 3 different precursor batches of dimethylhydrazine (DMHy). A DMHy batch was identified which gave background oxygen concentrations in Al-containing layers below the SIMS detection limit (2-8E16 cm^-3) with 0.2% nitrogen content. Therefore, providing that suitable growth conditions are chosen such that nonradiative centres other than oxygen do not form, this DMHy precursor batch is expected to give In_xGa_(1-x)N_0.002As_0.998 quantum wells with good luminescence properties.