Antiphase domains in GaAs grown by metalorganic chemical vapor deposition on silicon-on-insulator

Abstract

Distinct antiphase domain structures in GaAs epitaxial layers grown on a Si/SiO2/Si-substrate structure by metalorganic chemical vapor deposition have been revealed by using a silicon etchant (HF/HNO3). The antiphase is characterized by the [011]-oriented etching textures which rotate 90° between adjacent domains. The corresponding lattice rotation is further confirmed by a convergent beam electron diffraction technique. The size of the antiphase domains is found to increase with increasing film thickness and to grow upon annealing at temperatures above 700 °C. The maximum size of the domain, however, is found to be limited by the film thickness. The majority of the domain boundary lines revealed by chemical etching on the (100) surface do not correspond to any crystalline orientation. Only small segments are found to orient along [011], [010], [021], and, occasionally, [031] and [041] directions. Cross-sectional transmission electron microscopy studies confirmed that the boundaries are generally in curved configurations or zigzag configurations constituted of (011), (010), and (121) planes. All the boundaries are initiated at the interface and propagate through the film in the growth direction. Diffraction contrast experiments show a stacking-faultlike contrast of intrinsic type, indicating an inward relaxation of the lattice planes at the boundary. The rapid chemical reaction of the boundary with the silicon etchant, the intrinsic nature of the lattice distortion at the boundary, and the curved configuration of the boundary indicate that the boundary atoms are replaced by Si atoms. The higher concentration of Si atoms at the antiphase boundary has further been verified by energy dispersive x-ray analysis. In view of the reduction of bond distortion energy, the segregation of Si atoms at the antiphase boundary eliminates the highly distorted GaGa and AsAs bonds and is, therefore, an energetically favorable process. The possible antiphase boundary structure and a mechanism for its migration are discussed. Spatially resolved photoluminescence and cathodoluminescence studies reveal that both the antiphase boundaries and the defective interfacial regions contain nonradiative recombination centers. The luminescence efficiency of the domains increases strongly after annealing.

GaAs/Si epitaxial integration utilizing a two-step, selectively grown Ge intermediate layer

“…Correspondence of the bright features in the SE image and the dark features in CL image leads us to conclude that the stacking faults act as non-radiative recombination centers. This conclusion is not surprising since APDs in GaAs are a type of stacking fault that are known to cause non-radiative recombination [26]. The high density of non-radiative recombination sites at stacking faults leads to a lower radiative emission from the GaAs grown on the Ge/Si wafer prepared with the standard epitaxial process compared to similar III-V structures grown on Ge substrates.…”

Effect of bulk growth temperature on antiphase domain boundary annihilation rate in MOCVD-grown GaAs on Si(001)

“…No other growth conditions were changed. The through-thickness APB density for each sample was analyzed using a similar method to that presented by Georgakilas et al [17] [13,17,20,23] and can therefore improve contrast in imaging and differentiate APBs from other features. Images of the sample surfaces in various areas were taken in plan view with a FEI Nova NanoSEM 430 scanning electron microscope (SEM) operating at 5 kV.…”

“…Clearly, {110} oriented APBs are not conducive for self-annihilation. However, it has been observed experimentally with transmission electron microscopy (TEM) that while APBs in GaAs typically form along {110} planes they have a tendency to change their plane of propagation during growth [13][14][15][16][17]. Georgakilas et al, also analyzed the through-thickness APB density in a GaAs film grown on Si and found that the APB density decreased with increasing distance from the GaAs/Si interface, an indirect indication that the APBs were propagating along inclined planes and self-annihilating [17].…”

Research of surface morphology in Ga(In)As epilayers on Ge grown by MOVPE for multi-junction solar cells

“…APDs are connected by anti-phase boundaries (APBs), and domains of differing orientation are separated by an APB. Since APBs act as non-radiative recombination surfaces, providing deep levels in the forbidden gap [11], the successful realization of GaAs/Ge devices depends on the ability to grow a high-quality APDfree heterostructure.…”