n,p柱宽度对超结SiGe功率二极管电学特性的影响  

Effects of p and n pillar widths on electrical characteristics of super junction SiGe power diodes

作　　者：高勇[1] 马丽[2] 张如亮[1] 王冬芳[1] 

机构地区：[1]西安理工大学电子工程系,西安710048 [2]西安理工大学应用物理系,西安710048

出　　处：《物理学报》2011年第4期633-639,共7页Acta Physica Sinica

基　　金：陕西省教育厅专项科研项目(批准号:09JK640)资助的课题~~

摘　　要：结合SiGe材料的优异性能与超结结构在功率器件方面的优势,提出了一种超结SiGe功率二极管.该器件有两个重要特点:一是由轻掺杂的p型柱和n型柱相互交替形成超结结构,取代传统功率二极管的n-基区;二是阳极p+区采用很薄的应变SiGe材料.该二极管可以克服常规Sip+n-n+功率二极管存在的一些缺陷,如阻断电压增大的同时,正向导通压降随之增大,反向恢复时间也变长.利用二维器件模拟软件MEDICI仿真分析得到以下结论:与相同结构尺寸的常规Si功率二极管相比较,20%Ge含量的超结SiGe功率二极管,反向阻断电压提高了1.6倍,正向压降减小了约60mV(正向电流密度为10A/cm2时).虽然反向恢复时间没有明显减少,但反向峰值电流密度降低了17%,软恢复特性也显著提高,后者的软度因子是前者的2倍多.超结部分的p型柱和n型柱宽度是器件设计中的重要结构参数,本文重点讨论了该参数对器件电学特性的影响:柱区宽度越小,阻断电压越高,漏电流越小,但同时正向压降有所增加.柱区宽度对反向恢复特性的影响没有明显的单调性,柱区宽度过小时会出现硬恢复现象.通过对该结构参数进行优化设计可以同时获得低通态压降、高阻断电压、快速恢复的特性.By combining merits of both SJ structure and SiGe material,a novel super junction（SJ） SiGe power diode is presented.The two important characteristics of SJ SiGe diode are its columnar structure of alternating p/n pillars substituting n-base region of conventional Si p ＋ n-n ＋ diode and its far thinner strained SiGe p ＋ layer,which can overcome the drawbacks of conventional Si power switching diodes,such as when the reverse blocking voltage is higher,the forward voltage drop is larger and the reverse recovery time becomes longer.For the SJ SiGe diode with 20% Ge content,the following conclusions can be obtained compared with comparable conventional Si power diodes：the breakdown voltages increase by 1.6 times,the forward voltage drop is reduced by 60 mV（at a current density of 10 A /cm2） and the softness factor S increases by 2 times.Though the reverse recovery time is shortened slightly,the peak reverse current density decreases by 17% and the soft recovery characteristics is improved notedly.The key parameters of the p and n pillar widths have imporant effects on the forward conduction characteristic,reverse blocking characteristic and reverse recovery characteristic of SJ SiGe power diode.The smaller the pillar width becomes,the higher the breakdown voltage is and the lower the reverse leakage current is,whereas the forward voltage drop increases slightly.The pillar width has no obviously monotonic effect on the reverse recovery characteristic.If the width is too small,the soft reverse recovery characteristic is degenerated.To optimize the parameter of pillar width,we can obtain excellent SJ SiGe diode with fast recovery speed,high breakdown voltage and low forward drop at the same time.

关 键 词：超结 锗硅二极管 n p柱宽度 电学特性 

分 类 号：O472.4[理学—半导体物理]