[13a-A21-1~10] 15.4 III-V-group nitride crystals

[13a-A21-9] Determination of the Sb Occupation-Site in MOCVD-grown GaN_1-xSb_x using X-ray Absorption Fine-Structure Measurements

〇Takao Miyajima¹, Daisuke Komori¹, Ryoma Seiki¹, Toshiaki Ina², Kiyofumi Nitta², Kenta Suzuki¹, Tetsuya Takeuchi¹, Tomoya Uruga², Satoshi Kamiyama¹, Motoaki Iwaya¹, Isamu Akasaki¹ (1.Meijo Univ., 2.JASRI)

Keywords:nitride semiconductor, x-ray absorption fine-structure, GaSb

GaN_1-xSb_x is an attractive alloy semiconductor for realizing highly conductive p-type GaN-based semiconductors, which are still required for GaN-based laser diodes with a higher optical power. This is because the activation energy of acceptors can be reduced in GaN_1-xSb_x by adding GaSb to GaN. This characteristic is attributed to the fact that the top energy level of the valence band of GaSb is closer to the vacuum energy level than that of AlN, GaN and InN. The growth of the homogenous GaN_1-xSb_x is, however, difficult because the atomic bond length of Ga-Sb is 1.36 times greater than that of Ga-N. It has been confirmed that the average lattice constant of GaN_1-xSb_x increased with increasing Sb composition, but it has not been reported whether the Sb atoms occupy the anion site of GaN-based wurtzite structure or not. In this study, we investigated the local structure around Sb atoms in GaN_1-xSb_x using x-ray absorption fine-structure (XAFS) measurements at SPring-8 of the 8GeV synchrotron radiation facility, and concluded that most Sb atoms in the GaN_1-xSb_x do not occupy the ideal anion (group V atom) site of a GaN-based wurtzite structure although Sb atoms are contained in it.