Structural Properties of m-Plane InAIN Films Grown on ZnO Substrates with Room-Temperature GaN Buffer Layers

摘要

The growth of m-plane In_xA_(1-x)N (0.34 < x < 0.89) films was achieved using ZnO(1100) substrates and pulsed-laser-deposited room-temperature-commensurate GaN buffer layers. Atomic force microscopy images of m-plane In_(0.39)Al_(0.61) N exhibited an atomically flat stepped-and-terraced structure. The growth temperature leading to compositional instability of m-plane In-rich InAIN was as low as 300℃, which indicates that the low-temperature growth technique is necessary for the epitaxial growth of m-plane InAIN. Although 100-nm-thick m-plane In_xAl_(1-x)N (x = 0.39 and 0.36) films were coherently grown, InAIN films with an In composition greater than 50% were partially relaxed. Furthermore, it was determined that the strain relaxation preferentially takes place along the c-axis. The full width at half maximum values for the X-ray rocking curves of a coherently grown m-plane In_(0.39)Al_(0.61)N film were as small as ～250 arcsec, while the crystalline quality of lattice-relaxed In-rich InAIN films was poor. These results indicate that the selection of substrates with appropriate lattice constants is essential for obtaining high-quality m-plane InAIN.