一、引言分子束外延(MBE)是新近发展起来的制备化合物半导体薄膜的方法。生长过程包含一个或多个热分子束或原子束与晶体表面在超高真空(10~(-9)～10~(-10)托)条件下的反应。依照粘附系数的差别,严格控制入射分子流或原子流。外延薄膜的结构随分子束的相对流量改变,保持严格的化学配比。晶体生长受分子束相互作用的动力学过程支配,而异于常规的化学汽相淀积(VPE)和液相外延(LPE)中的准热力学平衡。分子束外延是在基础研究中出现的外延生长新方法。分子束外延能够精确地控制外延层的厚度和均匀性。例如,用计算机控制的分子束外延设备已生长出低于10(?)厚度的GaAs和 I. INTRODUCTION Molecular beam epitaxy (MBE) is a newly developed method for preparing compound semiconductor thin films. The growth process involves the reaction of one or more thermal molecular beams or atomic beams with the crystal surface under ultrahigh vacuum (10 -9 to 10 -10 Torr). According to the difference of adhesion coefficient, strictly control the incident molecular flow or atomic flow. The structure of the epitaxial film changes with the relative flux of the molecular beam, maintaining a strict stoichiometry. Crystal growth is governed by the kinetic processes of molecular beam interactions, but differs from the quasi-thermodynamic equilibrium in conventional chemical vapor deposition (VPE) and liquid phase epitaxy (LPE). Molecular beam epitaxy is a new method of epitaxial growth in basic research. Molecular beam epitaxy can precisely control the thickness and uniformity of the epitaxial layer. For example, GaAs with thicknesses below 10 (?) Have been grown using computer controlled molecular beam epitaxy