NEA GaN光电阴极第一性原理研究  

First principle study on NEA GaN photocathode

作　　者：任彬[1,2,3] 石峰 郭晖 江兆潭[3] 程宏昌 焦岗成 苗壮 冯刘 

机构地区：[1]微光夜视技术重点实验室,陕西西安710065 [2]北方夜视科技集团股份有限公司,云南昆明650223 [3]北京理工大学物理学院,北京100081

出　　处：《红外与激光工程》2015年第9期2752-2756,共5页Infrared and Laser Engineering

基　　金：微光夜视技术重点实验室基金(J20130501)

摘　　要：采用基于密度泛函理论(DFT)框架下广义梯度近似投影缀加平面波方法,在六方结构Ga N结构优化的基础上,计算了Ga N(0001)A面吸附Cs后功函数变化,指出吸附系统表面形成了一个有效的Ga N-Cs电偶极子层,降低了原本的Ga N表面势垒,形成更加有利于电子逸出的外光电发射效应特性。接着图示吸附Cs、O后的电子结构,指出吸附原子和衬底之间的键合。六方结构Ga N材料的光学性质通过Kramers-Kronig关系得出。根据Ga N的介电函数谱,得出了254nm光波长下以Ga N为激活层材料的反射式光电阴极在不同少子扩散长度下的内量子效率。计算结果表明六方结构Ga N(0001)A面是可见光盲光电阴极的优良发射表面,且254 nm处的量子效率可达到60%,远大于碱金属卤化物紫外光电阴极。Using the projected augmented wave potential based upon the density functional theory within the gradual gradient approximation approach, after the optimization of wurtzite structure GaN, the affinity variation of Cs atoms adsorbed on GaN （0001）A surface was calculated, which proving that an effective GaN-Cs dipole layer was formed, and be good for electrons escaping form the substrate. The electronic structure of adsorbed Cs and O on GaN （0001）A surface was also calculated, which pointed out the bonding of Cs and GaN substrate. Furthermore, the internal quantum efficiency of reflect photocathode of GaN material on various minority carder diffusion length were derived from dielectric functions theoretically. The calculated results demonstrate that GaN （0001）A surface is an excellent emitter for visible-blind photocathode, and the efficiency at 254nm can reach up to 60%, far more than other alkali halide UV photocathodes.

关 键 词：GAN 第一性原理 可见光盲 负电子亲和势 

分 类 号：TN23[电子电信—物理电子学]