Laterally Overgrown GaN on Patterned GaAs (001) Substrates by MOVPE

Abstract

The characteristics of single‐crystal GaN regions obtained by selective‐area and subsequent lateral overgrowth on stripe‐patterned GaAs (001) substrates by MOVPE were studied. Under certain growth conditions, the surface kinetics of the MOVPE process result in lateral‐growth of both hexagonal‐GaN (h‐GaN) and cubic‐GaN (c‐GaN) stripes with the appropriate mask stripe orientation, namely [110] and [1$ \bar 1 $0], respectively. The facet structure comprises the c‐GaN stripes surrounded with (111) B facets and mixture facets of (311) A, (111) A, and an inversed (111) B for the stripe window opening along the [110] and [1$ \bar 1 $0] directions, respectively. The cross‐sectional TEM micrographs showed that the h‐GaN is laterally overgrown along the (111) B facets of the c‐GaN stripes. For the [110]‐stripes, the laterally overgrown h‐GaN regions contained a very low density of dislocations (<108 cm—2). On the other hand, for the [1$ \bar 1 $0]‐stripes, a large reduction of stacking fault density was found in the overgrown c‐GaN regions. We demonstrated that both high quality h‐GaN and c‐GaN films were successfully grown on the stripe‐patterned GaAs (001) substrates by MOVPE.

Reduction of Planar Defect Density in Laterally Overgrown Cubic-GaN on Patterned GaAs(001) Substrates by MOVPE

“…The results show that the h-GaN generation occurs only on the mask and finally terminated in the coalescence regions over the mask. Further detailed study of h-GaN generation mechanism will be discussed elsewhere [9]. Furthermore, the sharp triangular voids surrounded by the (111)B facets are also left behind in the middle of mask regions.…”

“…In addition, we see that an inversedmesa shape with stable (111)B facets are formed on the mask regions ( Fig. 1a) [8,9]. Hence, the growth results in the triangular voids with a mesa shape formed by the (111)B facets above the mask regions.…”

“…On the other hand, there are no detailed study concerning to the crystal properties of ELO of cubic-GaN (c-GaN). In our previous work, we reported that the c-GaN structures using SAG could be controlled by mask fill factor, mask direction and growth temperature [6][7][8][9]. The selectively grown c-GaN films with a high cubic phase purity were obtained using the [1 1 10]-oriented stripe-patterns with a suitable growth area-width.…”

“…The selectively grown c-GaN films with a high cubic phase purity were obtained using the [1 1 10]-oriented stripe-patterns with a suitable growth area-width. Additionally, it has been observed that the lateral overgrowth of both h-GaN and c-GaN on the stripe-patterned GaAs (001) substrates were realized, resulting in a very low density of extended defects in the laterally overgrown h-GaN and c-GaN films [9]. The aim of this study is to provide high quality c-GaN films with low planar defect (namely stacking faults and twins) density obtained by controlling the cubic-to-hexagonal structural transition [9] during the lateral overgrowth process using an appropriate mask stripe orientation via MOVPE.…”

Growth mechanism and structural characterization of hexagonal GaN films grown on cubic GaN (111)/GaAs (111)B substrates by MOVPE

“…Sapphire has been the commonly used substrate material for the growth of the hexagonal GaN attention [1][2][3][4][5][6], because the difference in the thermal expansion coefficients between GaAs and GaN is less than those of other materials such as Si, 6H-SiC and sapphire. In order to improve the crystal quality of the h-GaN films, the growth of hGaN on GaAs (1 1 1) substrates with a cubic GaN (c-GaN) (1 1 1) intermediate layer has been proposed [3,4].…”