Precise and efficient ex situ technique for determining compositions and growth rates in molecular-beam epitaxy grown semiconductor alloys

A technique based on the principle of coupling an evanescent wave via a prism into a semiconductor thin film has been used to determine simultaneously the composition and the thickness of II–VI semiconductor ternary alloys. This approach, which determines the indices of refraction n with high precision (at least 0.1%), and also concurrently determines the epilayer thicknesses with an uncertainty of less than 0.5%, has been applied to a series of molecular-beam epitaxy grown ternary alloy families; $Zn1−xCdxSe,$ $Zn1−xMgxSe,$ $Zn1−xBexSe,$ $Zn1−xMnxSe,$ and $ZnSe1−xTex.$ The composition determined by x-ray measurements allows one to generate a calibration between n and the alloy composition, which is used subsequently to derive the alloy composition of the ternary specimen by measuring only its value of n. Since the prism coupler method also determines the thickness of the film, the growth rates are also obtained concurrently.