Study of the partial decomposition of GaN layers grown by MOVPE with different coalescence degree

Effects of the diameter of thermally generated nanopits on carrier dynamics in AlGaN/GaN heterostructures

“…The increase in the diameter of nanopits at relatively high annealing temperatures, 1150°C and 1200°C, reflects the start of the AlGaN thermal decomposition process. Indeed, thermal decomposition preferentially starts on dislocations sites generated on the top surface of the epitaxial layer 29,36,38 Our results agree well with the findings by Kuball et al, 39 who have shown that AlGaN annealed in nitrogen ambient starts to decompose at annealing temperatures higher than 1150°C.…”

Observation of the early stages of GaN thermal decomposition at 1200 °C under N 2

“…Recently, we investigated the relationships between the initial coalescence degree of GaN and its decomposition kinetic at 1200 °C under N 2 [22]. We demonstrated that decomposition of complete coalesced GaN can be performed nearly layer by layer and decomposition of incomplete coalesced GaN leads to anisotropy etching with high surface degradation [22]. The decomposed GaN layer until 0.6 µm of thickness loss showed crystalline property comparable to the as grown GaN layer.…”

“…However, little attention has been devoted to the effect of initial surface morphology on the partial GaN decomposition process. Recently, we investigated the relationships between the initial coalescence degree of GaN and its decomposition kinetic at 1200 °C under N 2 [22]. We demonstrated that decomposition of complete coalesced GaN can be performed nearly layer by layer and decomposition of incomplete coalesced GaN leads to anisotropy etching with high surface degradation [22].…”

Effect of GaAs substrate orientation on the growth kinetic of GaN layer grown by MOVPE

“…GaN can be crystallized in either hexagonal (wurtzite) or cubic (zinc blende) structure depending on both the substrate type and growth conditions. The hexagonal phase is generally obtained grown on substrates, such as sapphire and 6H-SiC [3,4], while cubic GaN layers, which exibit higher carrier mobility and doping efficiencies [5][6][7] when compared to hexagonal GaN layers, can be grown on (001) GaAs [8], (001) Si [9] and 3C-SiC [10] substrates. In the case of the GaAs substrate, which is advantageous for device fabrication, both zinc blende and wurtzite phases may coexist in the GaN layer because of the small difference between formation of the different phases [11,12].…”