HETEROGENEOUS HYDRIDE PYROLYSIS IN A CHEMICAL BEAM EPITAXY CRACKER CELL AND GROWTH OF HIGH-QUALITY INP

The decomposition of phosphine and arsine in a chemical beam epitaxy c racker cell was investigated with a quadrupole mass spectrometer. We h ave determined the kinetical parameters for a unimolecular reaction of the first order, i.e. the activation energy and frequency factor, fro m the decomposition efficiency as a function of temperature. These res ults are compared with data from literature. We find the lowest activa tion energies ever reported for the hydride pyrolysis, namely 72 and 4 8 W/mol for phosphine and arsine, respectively. This is due to the het erogeneous decomposition on catalytic molybdenum baffles inside the cr acker cell. Additionally, we have studied the impurity incorporation i n epitaxially grown bulk InP layers in relation to the efficiency of t his particular molybdenum containing cracker cell. Impurity levels wer e determined by fitting calculated Hall values to experimental data. T he best quality is achieved for the cracker temperature at which the e fficiency starts to saturate. At this cracker temperature, optimized m ass flow rates resulted in InP layers with a maximum mobility of 186 0 00 cm(2)/V s and impurity concentrations in the low 10(14) cm(-3) rang e. (C) 1997 American Vacuum Society.