Preventing trench defect formation in InGaN epilayers using Ga-migration-enhanced epitaxy

Abstract

The growth of InGaN by Ga-migration-enhanced epitaxy using metalorganic chemical vapor deposition is reported. Trench defects, which are usually associated with the generation of basal-plane stacking faults (BSFs), can be significantly diminished by this method. The surface morphology and luminescence characteristics of the deposited InGaN are consequently improved. It is demonstrated that the Ga-migration-enhanced epitaxy can inhibit the generation of BSFs and thus prevent the formation of trench defects in InGaN epilayers.

Surface Evolution of Thick InGaN Epilayers with Growth Interruption Time

“…29,30 Besides, previous research studies have suggested that more BSFs are formed in the case of low atomic mobility. 8,31,32 The BSFs may induce stacking mismatch boundaries and then trigger the formation of V-pits, resulting in the clustered V-pits in trench defects. 33,34 3.2.…”

“…It is well known that the In adatoms act as surfactants in the epitaxy process of InGaN, and That is, the quantity of metal adatoms is probably less than 1 ML, resulting in lowered surface of Ga adatoms and the subsequent formation of BSFs and related trench defects. 8 Moreover, PL characteristics were also measured using a Horiba JYHR800 spectrometer with a 325 nm excitation laser beam, as shown in Figure 5b. In the measurements, the diameter of a laser beam spot is ∼30 μm, and the incident power is ∼0.31 mW.…”

“…6,7 In addition, the low thermal stability of InN caused by the relatively weak In−N bond may also contribute to indium (In) surface segregation. 8 All these typical problems are generally reflected in the surface morphology of InGaN epilayers, which deviates from the desired defect-free morphology with step flow in the two-dimensional growth mode. Moreover, the surface morphology may further deteriorate with the increase in the thickness and In composition of InGaN epitaxial layers.…”

“…Due to the large difference in InN and GaN interatomic spacing, leading to a large immiscibility gap in InGaN, severe phase separation usually takes place in thick and/or high indium composition InGaN through the process of spinodal decomposition . The mismatch strain in the InGaN grown on GaN often results in indium surface segregation (i.e., composition pulling effect), dislocations, and their associated defects such as V-shape pits (V-pits). , In addition, the low thermal stability of InN caused by the relatively weak In–N bond may also contribute to indium (In) surface segregation . All these typical problems are generally reflected in the surface morphology of InGaN epilayers, which deviates from the desired defect-free morphology with step flow in the two-dimensional growth mode.…”

“…8 , 2.1 × 10 8 , 2.0 × 10 8 , and 1.9 × 10 8 cm −2 , respectively, by taking b = 0.5185 nm, while for the InGaN epilayers, the D S values are 3.6 × 10 8 , 2.8 × 10 8 , 2.0 × 10 8 , and 2.2 × 10 8 cm −2 , respectively, by taking b ≈ 0.5303 nm calculated from the data of RSMs. The fwhm of the InGaN layer, that is D…”