薄GaAs层化学腐蚀及它的表面结构

用pH=7±O.05的H_2O_2-NH_4OH溶液,在5±1℃,对晶句是(100)的高阻或浓度为2×10~(13)cm~(-3)的n型GaAs衬底进行腐蚀试验.发现腐蚀速率不但与搅拌有关,且在最初半分钟左右或开始250～500(?)的GaAs腐蚀,其腐蚀速率比更长时问或更深腐蚀时要快得多.分析表明,NH_4OH向GaAs与溶体界面的扩散很可能是腐蚀过程的限制步骤.对腐蚀后的残余氧化层进行测试分析,认为化学腐蚀后在表面有一层极薄的氧化物层,接着是过渡层.用HCI或NH_4OH水溶液清洗则可去除氧化物层并缩小过渡层.

Chemical Etching of Thin GaAs Layer and Its Surface Structure

(100) oriented either Cr-doped semi-insulating or n-type (n=1018cm-8) GaAs are etched by pH= 7±0.05 H2O2-NH4OH etchant at 5±l℃ and also washed by HCl:H2O = 1:1 or NH4OH:H2O = 1:10 solutions. The etching rate is influenced by stirring, and it is faster at the initial or at the first 250-500A etching. Analysis indicates that the diffusion of NH4OH toward the GaAs-solution interface is a most possible step limiting the etching process. It can be concluded from the measurement and analysis of residual oxidized layers that after etching there is a very thin residual oxide layer on the outermost surface, which is followed by a transition layer. The oxide and a part of the transition layer can be removed by aqueous solution of HC1 or NH4OH.