DECOMPOSITION BEHAVIOR OF NITROGEN PRECURSORS FOR P-TYPE DOPING OF PYROLYTIC AND PHOTOASSISTED MOVPE OF ZNSE

Work was carried out on the vapour pressure and decomposition characte ristics of three possible nitrogen precursors for p-doping of ZnSe, tr iallylamine (TAN), trimethylsilylazide (TMSiN), and bis[di(trimethylsi lyl)amido]zinc (BTM), under pyrolytic and photo-assisted conditions. T he vapour pressure and room temperature stability of the nitrogen prec ursors was determined using an in situ ultrasonic (Epison) monitor and the results have shown that TAN and TMSiN are well behaved at room te mperature with the following pressure-temperature relationship: logp(T orr) = 5.80 -1500/T and logp(Torr) = 6.78 -1513/T, respectively, both in close agreement with reported values. BTM, however undergoes decomp osition in the bubbler at room temperature shown by an initial high re ading on the Epison which then decreases. A mass spectrometry system w as developed to quantitatively measure the decomposition of nitrogen p recursors on a ZnSe surface under growth conditions of flow and temper ature and this showed that TAN appears to be stable below 450 degrees C and shows no significant enhancement with photoassistance. BTM appea rs to undergo some decomposition to a more volatile species at room te mperature and the precursor undergoes multi-step decomposition. TMSiN decomposes below 400 degrees C and shows significant photo-enhancement and is thus potentially a very good nitrogen precursor for p-type dop ing of ZnSe.