Growth of InP on GaAs (001) by hydrogen-assisted low-temperature solid-source molecular beam epitaxy

Abstract

Direct heteroepitaxial growth of InP layers on GaAs ͑001͒ wafers has been performed by solid-source molecular beam epitaxy assisted by monoatomic hydrogen ͑H ‫ء‬ ͒. The epitaxial growth has been carried out using a two-step method: for the initial stage of growth the temperature was as low as 200°C and different doses of H ‫ء‬ were used; after this, the growth proceeded without H ‫ء‬ while the temperature was increased slowly with time. The incorporation of H ‫ء‬ drastically increased the critical layer thickness observed by reflection high-energy electron diffraction; it also caused a slight increase in the luminescence at room temperature, while it also drastically changed the low-temperature luminescence related to the presence of stoichiometric defects. The samples were processed by rapid thermal annealing. The annealing improved the crystalline quality of the InP layers measured by high-resolution x-ray diffraction, but did not affect their luminescent behavior significantly.

Microstructural improvements of InP on GaAs (001) grown by molecular beam epitaxy by in situ hydrogenation and postgrowth annealing

“…22 For H ‫ء‬ -assisted MBE, the critical thickness, as observed by reflection high-energy electron diffraction, increased to at least 200 nm, a value which is ϳ40 times larger than expected. Additionally, these heteroepitaxial InP films showed good optical properties, with a band-to-band intensity at room temperature nearly one fourth the intensity for homoepitaxial InP grown under the same conditions.…”

“…28,29 The hydrogenation of semiconductors modifies both chemical reactivity and electrical conductivity, making them less reactive ͑passivated͒, and may remove surface states by terminating surface dangling bonds. 30 These might be some of the reasons for the improved epitaxy ͑DTD: C1-B2 ϳ 10 9 cm −2 ; C2ϳ 10 8 cm −2 ͒ and the highly improved emission 22 in the present H ‫ء‬ -assisted experiments ͑PL at room temperature similar to C1 and C2͒.…”

“…The growth and annealing conditions and the XRD results are detailed elsewhere. 22 The heterostructures were structurally characterized by transmission electron microscopy ͑TEM͒ techniques: selected area electron diffraction ͑SAED͒ and high-resolution TEM ͑HRTEM͒, carried out in JEOL thermoionic and fieldemission microscopes ͑a JEM-1200EX, operated at 120 keV, and a JEM-2010F, operated at 200 keV, respectively͒. The cross-sectional TEM ͑XTEM͒ and plan-view TEM ͑PVTEM͒ sample preparations consisted of classical routines of mechanical thinning, plus ion milling and subsequent plasma cleaning.…”