A Secondary Ion Mass Spectrometric Study of Ti Incorporation into Metal Organic Chemical Vapor Deposition Grown InP.

A detailed SIMS analysis of Ti incorporation in InP during metal organic chemical vapor deposition (MOCVD) growth is performed. The InP:Ti layers were grown by atmospheric pressure MOCVD at 650C using cyclopentadienyl-cycloheptatrienyl titanium as the organometallic source. In each growth run, a n-type and p-type InP substrate were used. SIMS analyses were performed in a KRATOS XSAM800/SIMS800 quadrupole instrument which employs the Atomika A-DIDA microprobe ion gun and in CAMECA IMS-3f ion micro analyzer. Depth profiles were obtained by monitoring positive secondary ions generated by an oxygen primary beam. Quantitation of Ti was done using Ti implanted n- and p-type InP substrates. It is found that Ti can easily be incorporated in InP by MOCVD to a level of wig 10 sup 19 cm sup -3. However, electrically active Ti concentration is estimated to be only wig 10 sup 16 cm sup -3. The Ti atomic concentrations obtained by SIMS were also confirmed by laser ionization mass spectrometry of the same samples. It was found that the InP layers grown on the n-type InP substrates contained roughly a factor of wig 1.5 higher Ti than the ones grown on p-type substrates. It is suggested that differences in the Ti concentration in the layers grown on different types of substrates is related to growth rate variations.