MOVPE Growth of Semipolar GaN on Patterned Sapphire Wafers: Growth Optimisation and InGaN Quantum Wells

We are able to achieve two different GaN semipolar surfaces by growing on patterned sapphire substrates: (101̄1) GaN on (112̄3) sapphire and (112̄2) on (101̄2). By this approach, the growth of a coalesced semipolar layer on a large area of about two inches diameter is possible. Well known from the c-plane direction, an in-situ deposited SiN interlayer could reduce the defect density also in semipolar directions. The influence of position and growth temperature of the SiN layer on the GaN layer quality was investigated. Using optimized growth conditions, the full width at half maximum (FWHM) of X-ray rocking curve peaks could be halved. Moreover, an optimized temperature profile during growth of the main layer helps to improve the crystal quality even further. First InGaN quantum wells (QWs) were deposited on these optimized semipolar surfaces. When transferring the c-plane QW growth conditions to (112̄2) GaN on (101̄2) sapphire, a lower growth rate and a reduced indium incorporation was observed. By using thicker quantum wells grown with a higher indium flux, the emission wavelength could be shifted to 500 nm. In the case of (101̄1) GaN on (112̄3) sapphire, high-quality quantum wells with an emission wavelength of about 525 nm have been achieved.