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前言 以前制作单晶薄膜的外延法,已经工艺上应用的有气相外延和液相外延两种。但对某些要求,如很薄,均匀,结构复杂的外延层则不适用。最近几年发展了一种新的外延技术—分子束外延。进行研究的主要为美国的贝尔实验室(BTL)和IBM两家。另外英国和日本也在进行研究。在日本,高桥氏最先着手了分子束外延的研究工作,他这次主要介绍了分子束外延的原理,设备,应用以及发展前景等。现将座谈内容综述如下: 一、分子束外延 1.原理 首先谈分子束的产生,它是由一个钢笔筒那么大小的Knudseu炉,内装组成元素蒸发源,在超高真空10~(-10)毛下蒸发成束状射向衬底而外延生长单晶薄膜(其能量小于1电子伏。例如当分子束(如GaAs)连续射到衬底(如GaAs)上面生成GaAs,但并不是所有的元素都生成GaAs,而是一部分反射掉,一部分进入表面。分子束生长单晶决定于能量适应系数和动量适应系数。它可以用分子束射到衬底上停留时间τ来表示。当τ→∝则分子附着在衬底表面,反之,τ→0则分子束反射可用下式表示: τ=A_(exp)(E_a/K_T) 当晶体温度升高时,则停留时间短,反之则长。而且A.E_a与晶向有关。 有时我们用粘付系数来表示,即堆积分子束与入射分子束之比,若粘付系数为1,则入射分子束全部堆积,若付着系数为0,则全部反射,对GaAs衬底?
Preface The previous epitaxial growth of single crystal film, has been applied in the process of vapor phase epitaxy and liquid phase epitaxial two. But for some requirements, such as thin, uniform, complex structure of the epitaxial layer is not applicable. In recent years, a new epitaxy technology, molecular beam epitaxy, has been developed. The main research carried out by the United States Bell Laboratories (BTL) and IBM two. In addition, the United Kingdom and Japan are also studying. In Japan, Takahashi pioneered the research work of molecular beam epitaxy, and this time he introduced the principle, equipment, application and development prospect of molecular beam epitaxy. The discussion is summarized as follows: First, the molecular beam epitaxy 1. Principle First of all talk about the molecular beam generation, which is a penknife so Knudseu furnace, built-in elemental evaporation source, ultra-high vacuum 10 ~ (-10) For example, when a molecular beam (such as GaAs) is continuously emitted onto a substrate (such as GaAs) to generate GaAs, not all of the GaAs is generated by epitaxial growth of a single crystal thin film The elements all generate GaAs, but some of them are reflected and some enter the surface.Molecular beam growth single crystal depends on the energy adaptation coefficient and momentum adaptation coefficient.It can be expressed by the residence time τ of molecular beam incident on the substrate.When τ → α The molecule is attached to the surface of the substrate, whereas, τ → 0 then the molecular beam reflection can be expressed as follows: τ = A_ (exp) (E_a / K_T) When the crystal temperature increases, the residence time is short, A.E_a is related to the crystal orientation. Sometimes we use the sticky coefficient to express that the stacking molecular beam and the incident molecular beam ratio, if the adhesion coefficient is 1, then all the incident molecular beam accumulation, if the coefficient of 0, then all Reflections on the GaAs substrate?