[22a-H121-1~11] 15.4 III-V-group nitride crystals

▲ [22a-H121-9] Growth and characterization of inversion domain reduced semipolar (10\overline{1}3) GaN grown on Si (001) substrate

〇Hojun Lee¹, Siyoung Bae¹, Kaddour Lekhal¹, Akira Tamura¹, Manato Deki², Yoshio Honda², Hiroshi Amano^2,3 (1.Nagoya Univ., 2.CIRFE, 3.ARC)

Keywords:semipolar GaN,sputtered AlN,MOVPE

Semipolar (10\overline{1}3) GaN film was grown using the AlN/GaN supperlattices (SLs) interlayer on Si (001) substrate with sputtered AlN (sp-AlN) buffer layer. In order to obtain improved quality of semipolar (10\overline{1}3) GaN film, 3-type interlayers used high temperature AlN (HT-AlN), multi-AlN (HT/LT) and AlN/GaN SLs interlayers. The growth procedures were as follows : 45 nm thickness of sp-AlN buffer layer grown on Si (001) substrate by DC sputter then GaN and interlayers regrown by metal-organic vapor phase epitaxy (MOVPE). The growth of HT and LT-AlN interlayer parameters, such as a growth temperature, thickness and pressure were 750 °C, 1050 °C, 20 nm and 100 torr, respectively. In addition, AlN/GaN SLs interlayer was grown at 1040 °C and the thickness was 200 nm. The SLs pair was 25. All of the samples were same for GaN growth, the growth temperature, V/III ratio and pressure were 1040 °C, 36 and 100 torr, respectively. The experimental results showed that the AlN/GaN SLs interlayer significantly affect the crystal quality of subsequently grown on semipolar (10\overline{1}3) GaN film. To investigate the surface morphologies of the semipolar (10\overline{1}3) and (10\overline{1}\overline{3}) GaN films, 10 μm x 10 μm AFM measurement was carried out. Firstly, we measured the (10\overline{1}3) surface and then the Si substrate was removed by using a mixed etchant such as HF and HNO₃ in order to observe the density of inversion domain (ID) on the (10\overline{1}\overline{3}) surface. The value of ID density significantly decreased from 2.2E7 to 3E6 /cm^-2 with using the AlN/GaN SLs interlayer. This result imply that interlayer of AlN/GaN SLs have effect to annihilate ID. Also, HR-XRD analysis observed that there was reduction in rocking curve of the full width at half maximum (FWHM), both || [\overline{3}032] and || [1\overline{2}10] direction, respectively. Also, the PL result indicated that the near band edge (NBE) emission intensity increased with using the SLs interlayer. For these results suggested that the improved quality of semipolar (10\overline{1}3) GaN film can be obtained by AlN/GaN SLs interlayer.