Growth and in-plane optical anisotropy of crystalline quality enhanced non-polar m-plane ZnO(GaN) films on trenched (100) LiAlO2 substrates

Structural and optical properties of nearly stress-free m-plane ZnO film on (100) γ-LiAlO2 with a GaN buffer layer by metal-organic chemical vapor deposition

“…2. Seen from curve A, the E 2 (high) mode of ZnO is located at 436.7 cm À1 , which is very close to that of the bulk ZnO free of stress (437 cm À1 ) [19]. And the two peaks located at 534.6 cm À1 and 572.4 cm À1 in curve A are attributed to the A 1 (TO) and E 2 (high) modes of GaN, respectively [17].…”

“…Using the pressure coefficient (5.2 Â 10 À9 cm À1 Pa À1 ) determined by Mitra et al [21], we calculated that the epitaxial ZnO film was under slight tensile stress, about 5.77 Â 10 7 Pa, which was much smaller than those of ZnO epilayers deposited on other substrates [22,23]. Usually, ZnO films deposited on LAO wafers were under compressive stress [13,19], so the tensile stress is believed to be introduced by the GaN buffer layer. Two factors mainly influence the stress state of the ZnO epitaxial film: (1) À6 K À1 , respectively [24].…”