物理学报2018，Vol.67Issue(5)：244-253,10.DOI:10.7498/aps.67.20172213
外加电场和Al组分对纤锌矿AlGaN/GaN量子阱中的电子g因子的影响
Effects of external electric field and Al content on g factor of wurtzite AlGaN/GaN quantum wells
摘要
Abstract
In this paper, we study the effects of external electric field and Al content on the transverse and longitudinal g-factor (g⊥ and g//) and its anisotropy (δg) of wurtzite AlGaN/GaN quantum wells (QWs). The?g⊥=(g⊥?g0)=gbulk⊥ +gw and ?g// = (g// ?g0) = gbulk// are mainly contributed by the bulk structure (gbulk// and gbulk⊥ ) respectively, but the difference between gbulk// and gbulk⊥ is small and almost remains unchanged when the external electric field and Al content are varied. So the anisotropy of the g factor in AlGaN/GaN QWs induced by the bulk wurtzite structure is small, while the anisotropy induced by the quantum confined effect (gw) is considerable. When the direction of the external electric field is the same as (opposite to) the polarization electric field, the magnitudes of gbulk// and gbulk⊥ both increase (decrease) with increasing external electric field. This is induced mainly by the variations of envelope function and confined energy with the electric field. With the external electric field changing from ?1.5 × 108 V·m?1 to 1.5 × 108 V·m?1, the confined energyε1 increases slowly, and the magnitude of the envelope function at the left heterointerface increases. So the contribution to ?g⊥ from the heterointerface ΓInter is positive and increases slowly, and that from the well ΓW is negative and increases slowly in magnitude. The magnitude of ΓInter is larger than that of ΓW , but the magnitude of the latter increases more rapidly. All the above factors make the g-factor anisotropy δg>0 and decrease in magnitude with electric field increasing. With increasing Al content of the barrier, both 〈β〉1 (gbulk⊥ ) and 〈γ〉1 (gbulk// ) decrease if the strain effects are ignored (S1,2 = 0), because the confined energy decreases and the peak of the envelope function shifts towards the left heterointerface. By considering the strain effects (S1,2?=0), the magnitude of〈β〉1 (gbulk⊥ ) and〈γ〉1 (gbulk// ) increase with Al content increasing. The strain effect has a great influence on the confined potential V (z), leading to the rapid increase of β(z) when z > zp, which the situation for γ(z) is similar to. With increasing Al content, the magnitudes of ΓInter and ΓW both increase, but the magnitude of ΓInter is larger and increases more rapidly. Thereforeδg increases slowly. The magnitude of ?g⊥ first decreases with increasing Al content, then it increases with Al content increasing, and since gbulk⊥ <0 it increases more rapidly in magnitude. Results show that the g-factor and its anisotropy in AlGaN/GaN QWs can be greatly modulated by the external electric field, the Al content in the barrier, the strain effects and the quantum confined effect. Results obtained here are of great importance for designing the spintronic devices.关键词
自旋轨道耦合/Rashba效应/塞曼效应/g因子Key words
spin-orbit coupling/Rashba effect/Zeeman effect/g factor引用本文复制引用
李明,姚宁,冯志波,韩红培,赵正印..外加电场和Al组分对纤锌矿AlGaN/GaN量子阱中的电子g因子的影响[J].物理学报,2018,67(5):244-253,10.基金项目
国家自然科学基金(批准号:61306012)、河南省高等学校青年骨干教师(批准号:2015GGJS-145)、许昌学院杰出青年骨干人才计划、河南省自然科学基金(批准号:162300410237)和河南省科技发展计划(批准号:172102210470)资助的课题.Project supported by the National Natural Science Foundation of China (Grant No. 61306012), the Aid Project for the Leading Young Teachers in Henan Provincial Institutions of Higher Education of China (Grant No. 2015GGJS-145), the Aid Project for the Leading Young Talents of XuChang University, China, the Natural Science Foundation of Henan Province, China (Grant No. 162300410237), and the Development Project for Science & Technology of Henan Province of China (Grant No. 172102210470). （批准号:61306012）
