Process design of the pulse injection method for low-temperature metal organic vapor phase epitaxial growth of AlN at 800 °C

Abstract

The pulse injection (PI) growth method in which trimethylaluminium (TMAl) and NH 3 are alternately supplied was used to grow AlN layer at 800 °C. It was found that the process parameters in the PI method such as TMAl supply time ( τ TMAl), TMAl partial pressure ( P TMAl), and 1st H 2 purge time ( τ H1) had great influence on the crystal quality and surface morphology. Control of the growth rate to 1 monolayer (ML)/cycle resulted in highly improved crystal quality. 3.91×10 −4 mbar of P TMAl and 1 s of τ H1 were also found to be very effective in realizing high crystal quality showing narrow (0 0 0 2) and (1 0 1¯ 2) full-width at half-maximum (FWHM) values confirmed by high-resolution X-ray diffraction (HRXRD) rocking curve measurement. This is because the agglomeration of initial AlN islands and adducts formation by the gas-phase reaction could be suppressed under these conditions. According to the second ion mass spectroscopy (SIMS) measurement for the AlN layer grown by PI method (PI-AlN), the impurities concentrations of hydrogen, carbon, and oxygen showed several times lower levels than those of AlN layer grown by the conventional continuous method (C-AlN) at same 800 °C. Moreover, the impurities concentrations in PI-AlN layer were almost same with those of C-AlN grown at 1240 °C. It clearly shows the effectiveness of PI method in enhancing reduction reaction by NH 3.