Laser‐reflectometry monitoring of the GaN growth by MOVPE using SiN treatment: study and simulation

Abstract

The SiN treatment of the sapphire substrate for GaN growth induces a spectacular effect on the in situ reflectometry monitoring signal. Different growth modes are observed. The evolution of the reflectometry signal is simulated by the scattering theory approximation. The point-by-point analysis reveals that the roughness (rms) increases in the first region where the growth mode is dominated by the formation of isolated and three-dimensional hillocks. The rms attains a maximum value exceeding that authorized by the Rayleigh criteria. Another approach based on the effective medium approximation is used to simulate the entire reflectometry signal evolution. An effective refractive index and a growth rate profile are determined. The results obtained are in accordance with the observations done by the in situ ellipsometry monitoring. We have also studied the evolution of the defined recovery time as a function of the SiH 4 flow rate and the SiN duration. Based on the concept of a nano-epitaxial mask, induced by the SiN treatment of the sapphire surface, we have proposed a schematic model of the GaN growth that explains the recoverytime behavior.

Magnesium diffusion profile in GaN grown by MOVPE

“…The nucleation was done using the socalled ''Si/N-treatment'' procedure. The optimum growth conditions and the details of the Si/N-treatment growth process were reported elsewhere [6][7][8][9][10][11]. TMG, ammonia, silane and Cp 2 Mg were used as Ga, N, Si and Mg precursors with a mixture of H 2 and N 2 as the carrier gas.…”

Study of Surface and Interface Roughness of GaN-Based Films Using Spectral Reflectance Measurements

“…Fitouri et al found a similar behavior, once the coalescence process takes place. 27 The n f profile versus thickness is given in Fig. 8.…”

In Situ Spectral Reflectance Investigation of InAs/GaAs Heterostructures Grown by MOVPE

“…Moreover, because of spontaneous phenomena such as diffusion and segregation, other complex heterostructures have unstable physical properties during growth, leading to changes in solid composition, surface morphology, and growth rate (V g ). 17,18 Therefore, a large spectral range of the incident beam is needed to investigate some of these phenomena.…”