Investigations of in situ reflectance of GaN layers grown by MOVPE on GaAs (0 0 1)

Study of cubic GaN clusters in hexagonal GaN layers and their dependence with the growth temperature

“…In a previous study, we have shown that a significant improvement of the GaN layer structural quality can be achieved using substrate nitridation and low temperature buffer layer deposition before the growth of the epitaxial GaN layer at higher temperature. These steps prevent the decomposition of the GaAs substrate surface and enhance the GaN nucleation to initiate the growth of the GaN layer [18]. We also have shown, with other authors [19e21], that to obtain and stabilize the cubic phase, the deposition conditions (V/III ratio, growth temperature, GaAs substrate orientation) have to be optimized.…”

“…The largest oscillation damping is observed in sample # S 4 for which the GaN layer is grown at the highest temperature (850 C). The damping of the oscillation in the reflectance signal is attributed to changes in the surface morphology of GaN films and can be estimated by calculating the damping rate r d using the following equation [18]:…”

Analysis and simulation of the in-situ time-resolved reflectivity recorded during the growth of GaN on GaAs (110) substrate

“…First, we must point out that, in the case of normal incidence and a smooth surface film growing on the substrate, the complex reflectance amplitude is given as 6,[8][9][10][11][12][13] E Q -T A R G E T ; t e m p : i n t r a l i n k -; e 0 0 1 ; 1 1 7 ; 4 0 9…”

“…The GaAs (110) decomposition was enhanced using H 2 carrier gas and the absence of nitridation of the substrate compared with the results reported in previous works. [12][13] The growth temperature range below 900°C ensures the GaN thermal stability on GaAs but does not prevent the GaAs decomposition below the GaN layer being deposited. Regarding the presence at the early growth stages of a high initial growth rate followed by the damping of the reflectivity with constant growth rate, we assume the existence of two regimes.…”

Role of the TMG flow rate on the GaN layer properties grown by MOVPE on (hkl) GaAs substrates

“…Nonetheless, the use of a homogenous or gradual GaN buffer layer prevents the degradation of the GaAs surface during the active layer growth at high temperature. In our previous study, we reported a critical thickness of 100 nm that allows maintaining the thermal stability and reaching good quality of GaN/GaAs structures [12]. In addition to a smooth GaN surface and flat GaN/GaAs interface, several growth conditions must be adequately controlled.…”