肖特基金属对AlGaN/GaN二极管电学特性的影响  

Influence of Schottky Metal on the Electrical Characteristics of AlGaN /GaN Diodes

作　　者：邱旭[1] 吕元杰[2] 王丽 

机构地区：[1]中国电子科技集团公司第十三研究所,石家庄050051 [2]专用集成电路重点实验室,石家庄050051 [3]科技信息中心,北京100044

出　　处：《半导体技术》2014年第9期674-678,共5页Semiconductor Technology

摘　　要：肖特基金属影响AlGaN/GaN异质结材料的电学特性。在AlGaN/GaN异质结材料上分别制备得到铱/金(Ir/Au)、镍/金(Ni/Au)和铼/金(Re/Au)三种不同肖特基接触的二极管器件,基于电流电压(I-V)和电容电压(C-V)测试结果,计算得到了三者的沟道二维电子气(2DEG)密度。并通过薛定谔和泊松方程自洽求解计算得到了三者的肖特基接触势垒高度、导带底能带图和沟道2DEG分布情况。研究发现金属功函数越小,势垒高度反而越高,沟道2DEG密度越小,GaN侧的沟道三角形势阱变得越浅。这主要是由于金属功函数越小,电子能量越高,与AlGaN势垒层表面态的电子耦合作用越强所致。Schottky metal has a great influence on the characteristics of AlGaN /GaN heterostructure Schottky diodes. Three different metals of Ir /Au,Ni /Au and Re /Au were deposited on the AlGaN /GaN heterostructure to fabricate Schottky diodes with the same device structure,respectively. Based on the measured current-voltage（ I-V） and capacitance-voltage（ C-V） results of the prepared diodes,the densities of the channel two-dimensional electron gas（ 2DEG） for the three diodes were calculated and compared. Moreover, through self-consistently solving Schrodinger＇s and Poisson＇s equations, the characteristics of the three diodes were extracted and investigated,such as the Schottky barrier height,conduction band diagram and the distribution of the channel 2DEG. The research shows that as the metal function decreases,the Schottky barrier height doesn＇t increase correspondingly,but abnormally increases. Besides,the density of the channel 2DEG and the triangle quantum well depth of GaN both decrease with the increase of the metal function. This is mainly due to the stronger coupling between electrons in the metals and AlGaN surface donor electrons,which is induced by the higher electron energy with lower metal function.

关 键 词：ALGAN GaN 肖特基势垒高度 金属功函数 二维电子气(2DEG)密度 电子耦合 

分 类 号：TN304.23[电子电信—物理电子学] TN312