最近のNaフラックスを用いたGaN単結晶育成に関する研究(<小特集>バルク成長分科会特集 : 種結晶(核)からの結晶成長制御について)

抄録

Studies on the Na flux method for GaN single crystal growth were reviewed. Platelet single crystals of hexagonal wurtzite-type GaN (h-GaN) with a size of about 1 mm were obtained at 650-850'C in a stainless-steel sealed tube using NaN_3 as a source of Na and N_2. A mixture of h-GaN and cubic zinc-blend-type GaN (c-GaN) grains was precipitated at the bottom of a BN crucible at 570℃. Platelet h-GaN single crystals with a size over 5 mm in the longest direction grew at 750℃ and a constant N_2 pressure of 5 MPa for 200-450 h by introducing N_2 from the outside of a stainless steel container. Colorless transparent prismatic h-GaN single crystals of about 1 mm were obtained at a lower Na content in the starting Na-Ga melt. A carrier concentration n-type of 1-2×10^<18>cm^<-3> and a mobility of 100 cm^2 V^<-1>s^<-1> were measured at room temperature for platelet crystals of about I mm. The full-width at half-maximum (FWHM) of the rocking curve measured for 0004 X-ray diffraction peak was 25-32 arcsec.