Ga(N,P) Growth on Si and Decomposition Studies of the N-P Precursor Di- tert-butylaminophosphane (DTBAP)

Article abstract of DOI:10.1021/acs.organomet.0c00078

III/V semiconductors containing small amounts of nitrogen (dilute nitrides) are promising for applications such as lasers and solar cells. Metal-organic vapor-phase epitaxy (MOVPE) is a widely used technique for growing III/V semiconductors on an industrial scale, and the growth of dilute nitrides with this method is promising for later successful market entry. The main issues of dilute nitrides are carbon incorporation and low nitrogen incorporation efficiency of the conventional N precursors. Due to the high N incorporation efficiency and the low decomposition temperature of the As and N precursor di-tert-butylaminoarsane (DTBAA), a similar P- and N-containing precursor, di-tert-butylaminophosphane (DTBAP), was synthesized and purified on a laboratory scale. Growth studies using this precursor were carried out in this work realizing Ga(N,P)/GaP multi quantum wells on Si and GaP substrates. The structures show evidence of N incorporation, and good layer structures were confirmed by high-resolution X-ray diffraction. Following the influence of different growth parameters on the N incorporation, the growth rate and surface morphology were characterized to set a foundation for possible growth applications in the future. DTBAP shows many advantages over the conventional N source 1,1-dimethylhydrazine (UDMHy) such as a much lower decomposition temperature of 310 °C and the realization of Ga(N,P) layers grown at temperatures as low as 475 °C with a high N incorporation of over 10percent. Furthermore, the gas-phase decomposition of DTBAP has been studied with a real-time fast Fourier transform quadrupole ion trap mass spectrometer attached inline to the MOVPE reactor. The decomposition of DTBAP behaves very similarly to the As analogue DTBAA. On the one hand, the tert-butyl groups attached to DTBAP decompose radically, leading to the formation of isobutane, and decompose, on the other hand, by β-H elimination, leading to the formation of isobutene. Furthermore, the decomposition products indicate a direct cleavage of the P-N bond of the molecule, resulting in the formation of aminyl radicals (NH2?). The formation of NH2? explains the high N incorporation efficiency of DTBAP at low temperatures as well as its limitations due to loss of NH3 at higher temperatures.