外腔面发射激光器GaAs基质的酸性腐蚀

外腔面发射激光器的GaAs基质厚度大，热导率低，严重阻碍有源区热量的扩散，影响激光器功率的提高。为了去除激光器的GaAs基质，采用硫酸系酸性腐蚀，通过改变腐蚀液浓度和腐蚀温度来比较腐蚀液对GaAs基质的腐蚀影响，并采用原子力显微镜照片表征了腐蚀表面的粗糙度。结果表明，当腐蚀液的体积比V（H2SO4）:V（H2O2）:V（H2O）=1:5:10，腐蚀温度为30℃时，腐蚀速率适中，为5.2μm/min，腐蚀表面粗糙度2.7nm，腐蚀总体效果较为理想。较好的GaAs基质腐蚀效果为外腔面发射激光器衬底去除腐蚀阻挡层的选择性腐蚀提供了基本的保障。

Acid etching of GaAs substrate of external-cavity surface-emitting laser

Because of the large thickness and low thermal conductivity of GaAs substrate in external-cavity surface-emitting laser, the heat diffusion of active region is seriously impeded and the laser output power is difficult to improve. In order to remove the GaAs substrate, sulfate acid corrosion was used. The corrosion effects were compared with different concentration etching liquid at different temperature. Atomic force microscope photos were used to represent the roughness of etching surface. The results show that when the volume ratio of the etching liquid V(H2SO4):V(H2O2):V(H2O) is 1:5:10 and the temperature is 30℃, the moderate etching rate about 5.2μm/min and the 2.7nm roughness of etching surface is obtained. The good etching effect of GaAs substrate provides the basic guarantee for the next step of the substrate removal-selective etch of the stop-layer.