MOLECULAR LAYER EPITAXY AND ITS FUNDAMENTS

Molecular layer epitaxy (MLE) is a crystal growth method which is able to produce thin films by alternately injecting TMG and AsH3. At first, a self-limiting monolayer growth on a (100) surface was successfully obtained. In addition, we succeeded to obtain self-limiting monolayer crystal growth on a (111)B surface. No growth occurs on a (111)A surface. Furthermore, in-situ observation of the reaction of MLE on each substrate surface was performed by using a light-reflectance measurement. Here, a He-Ne laser beam penetrates through a window from outside to the surface of the substrate, and the reflected intensity is measured. By measuring the reflection on (100) and (111)B surfaces, the adsorption of Ga compounds during TMG supply, the reaction of the adsorbates during the evacuation period, and the surface reaction of the adsorbates with AsH3 may be distinguished. The characteristics of the reflection change during MLE were quite different on (111)A and on (111)B or (100) surfaces. A saturation phenomenon of the reflection intensity change may correspond to self-limiting growth in MLE.