衬底表面处理对原子层沉积法生长GaN薄膜的影响

Effect of Substrate Pretreatment on the Growth of GaN Films Prepared by Atomic Layer Deposition

摘要:

采用等离子增强原子层沉积技术于蓝宝石衬底上生长GaN薄膜,研究氮等离子体预处理衬底对薄膜结晶性能的影响。利用X射线衍射仪、扫描电子显微镜、原子力显微镜、X射线光电子能谱仪等手段对薄膜的晶体结构、表面形貌及薄膜成分进行表征和分析。结果表明,经预处理的蓝宝石衬底上生长的GaN薄膜晶体质量明显提高,沿c轴高度择优取向生长；光学带隙约为3.48eV；薄膜呈n型导电特性,电阻率为2.551×10-2Ω·cm,载流子浓度高达1.876×10¹⁹cm-3,迁移率为13.04cm²·V-1·s-1；薄膜中Ga元素主要与N元素以Ga-N键生成GaN。

Abstract:

High-quality GaN heteroepitaxy films were realized by using nitrogen plasma pretreatment of the sapphire substrate prior to the plasma-enhanced atomic layer deposition (PEALD) at 320℃. The crystal structures, surface morphology, elemental composition of the deposited GaN films were characterized by XRD, SEM, AFM and XPS. The results show that GaN films grown on the pretreated substrate exhibit improved crystalline quality with highly-preferred (002) growth direction. The as-grown GaN films are n-type with a carrier concentration up to 1.876×10¹⁹cm-3, resistivity of 2.551×10-2Ω·cm and the hole mobility of 13.04cm²·V-1·s-1. Most Ga elements form GaN with Ga-N bonds.