Observation of a New CuPt-Type Ordered-Phase with Orientation in the [111]A Direction in Al_0.5In_0.5P Alloy

Abstract

A new type of CuPt ordered-phase (CuPt-A) with orientation in the [111]A and [1̄1̄1]A directions was found in Al0.5In0.5P grown at 520° C on exact (001)GaAs substrate by gas-source molecular-beam epitaxy. Weak formation of conventional CuPt-B type ordered phase was also observed in the same AlInP layer. The surface reconstruction observed by RHEED during the growth was (2×2). At a growth temperature of 560° C the surface reconstruction was (2×1) and only conventional CuPt-B was formed. A step array parallel to [1̄10] and descending towards [110] was found to promote formation of the CuPt [111]A variant.

Atomic arrangement in a CuPt-B-type ordered GaAsSb layer grown by molecular beam epitaxy observed by cross sectional scanning tunneling microscope

“…1, there are bright spots that correspond to Sb atoms. The bright spots are partially aligned along the [1 12] and [112] directions separated by double-fold periodicity along the [1 1 1] and [11 1] directions, although the ordered regions are smaller than the completely ordered layers such as those in GaInP [2]. Fig.…”

“…Atomic ordering in III-V alloys reflects fundamental crystal growth processes on the surface during epitaxial growth [1,2]. Moreover, crystal properties with an ordered structure, such as a band gap, change as compared to the compositionally equivalent disordered structure [3].…”

“…The ordered structure was observed by cross-sectional transmission electron microscopy (TEM). TEM has commonly been used to characterize ordered structures [1][2][3][4][5][6]. Although TEM is a sensitive method of determining crystalline structure, it is best at detecting structures over a few ten nanometers thick.…”

Microstructure of CuAu-I-type ordered phase in III-V semiconductor alloys grown on a (001) substrate

“…Gomyo and co-workers 26,27 have investigated surface reconstructions, ordered-phase structures, and ordering direction in epilayers as a function of growth temperature, and found that there is one-to-one correspondence between the surface reconstruction and the type of ordered structures. From ab initio calculations, the reconstruction has been pointed out to change the values of the pairwise atomic interactions.…”

Quantitative analysis of variant III CuAu-I-type ordering of AlxGa1−xAs on (110), (111)A and (001) GaAs substrates using X-ray diffraction

“…Gomyo et al [23,24] experimentally found a correspondence between different surface configurations and different types of ordered structures, indicating the ordering is a surface rather than a bulk effect. Also thermodynamic calculations showed that different surface reconstructions can provide strong driving forces for CuPt A -type, CuPt Btype and triple-period structures of In 0.5 Ga 0.5 P grown on a GaAs(0 0 1) substrate [22,[25][26][27][28][29].…”