Highly uniform growth of 2-inch GaN wafers with a multi-wafer HVPE system

A new nozzle structure was developed in an improved multi-wafer hybrid vapor phase epitaxy (IHVPE) system by adding an inner dilution gas (ID) pipe between V and III groups gas channels. Experimental results showed that the thickness distribution of 2-inch GaN layer depended strongly on the flow rate of ID gas. The uniformity of film can arrive at ±3-4% by optimizing ID gas, which was better than that of ±30% grown in the old conventional multi-wafer hybrid vapor phase epitaxy (CHVPE) system. Meanwhile, the crystal quality and surface morphology were also greatly improved for GaN film by using the new reactor structure. The FWHM values of (002) and (102) were reduced from 342″ and 806″ to 207″ and 254″, respectively. AFM result of surface roughness (RMS, 10 μm×10 μm) of GaN layer was also lowered from 1.226 nm to 0.798 nm. It was partly because of the suppression of parasitic polycrystalline deposition due to the ID gas. This simple and economic method could provide an effective solution to simultaneously fabricate multiple GaN wafer with good thickness uniformity, high crystal quality and low cost.