用于GaAs IMPATT二极管的p~+-n_1-n_2-n~(++)多层汽相外延生长

本文报导一种采用双室矩形反应管生长p~+-n_1-n_2-n~(?)多层汽相外延技术.Zn和Sn分别为P型和N型掺杂剂.本技术能避免杂质存贮效应,使多层外延的浓度分布陡峭,p~+层中Zn对n_1层施主补偿小,n_1浓度下降一个数量级时n_1-n_2之间的过渡区为0.05～0.l微米,n_2-n~(?)之间的过渡区约0.5微米.本工作还研究了不同衬托倾斜角α和反应气流速度对外廷层横向均匀性的影响.实验证明,当α=22°时,运用局部气流加速法使外延层横向均匀性得到了明显改善.对于面积为4.5平方厘米的多层材料,5～7微米厚的n_2层,其横向厚度的最大偏差为±4.6%;亚微米厚的n_1层,其横向厚度是最大偏差为±17%;n_1层横向浓度的最大偏差为±5.1%.实验证明,用本技术生长的p~+-n_1-n_2-n~(?)多层材料,在保证有较高的输出效率的前提下,提高了器件的可靠性.材料性能优于传统的液相外延技术.制备IMPATT器件的典型结果为:在8千兆赫下最高的连续波输出功率达2.93瓦,效率20.5%、与Pt H-L结构的器件相比.工作寿命显然较长.文中还对Zn的掺杂行为进行了初步的讨论.

A p~+-n_1 -n_2 -n~(++) Multilayer Vapor Phase Epitaxial Growth Technique for GaAs IMPATT Diodes

In this paper, a technique for p+-n1-n2-n44 multilayer vapor phase epitaxial growth in a dual-chamber rectangular reactor is presented.Pure Zn and Sn are adopted as the doponts of P-type and N-type, respectively.With this technique the storage effect of impurity can be avoided and a sharp profile of the carrier concentration for the multilayer structure has been obtained. Zn in p+-epilayer exhibits only a slight compensation to the donor in n1 layer. When the concentration of n1 layer decreases an order of magnitude, the transient region between n1 and n2 is 0.05-0.1μm, and that between n2 and n* is about 0.5μm. It has been investigated that the lateral uniformity of the epilayer is influnced by the declination of the substrate holder α and the gas stream over the substrate. Experiments show that when α= 22° the lateral uniformity of the epilayer is significantly improved by partially accelarating the gas stream. For the multilayer material of the area of 4.5cm2, the maximal lateral deviation is ±4.6% with n2 layer thickness of 5-7μm, and ±17% for n1 layer of submicrometer; the maximal lateral deviation of n1 layer carrier concentration is ±5.1%.It has been shown that having ensured a higher efficiency the reliability of the devices is increased when the p+-n1-n2-n* multilayer material is used. The material properties are better than those of the conventional LPE materials. The typical results obtained for IMPATT diodes are that the highest CW power output is 2.93W at 8GHz, with the efficiency being 20.5%. The diodes have a longer operating lifetime than that of the Pt H-L structure.Finally, the behavior of Zn-doping is briefly discussed.