Preparation and characterization of I-III-VI_2 chalcopyrite semiconductor superlattice by Metalorganic Molecular Beam Epitaxy.

采用金属有机分子束外延（MOMBE）和分子束外延（MBE）生长了CuGaSe_2和CuAlSe_2外延层以及CuGaSe_2/CuAlSe_2超晶格.在GaAs（100）衬底上生长了c轴取向的CuGaSe_2和CuAlSe_2外延层。基于X射线衍射光致发光（PL），调制反射率和拉曼方法，外延层的质量是好的。制备了CuAlSe_2/CuGaSe_2/GaAs异质结构和层厚为200埃的超晶格。然而，XPS的深度分布没有反映超晶格的周期性。这说明涂层的平整度不高，需要改善表面形貌.用RHEED原位测量技术在GaAs（100）衬底上生长了CuGaSe_2和CuAlSe_2分子束外延层。通过调整Cu/III比和降低生长速率，实现了具有平坦表面的外延层。不 ...更多信息 制备了CuAlSe_2/CuGaSe_2/CuAlSe_2/GaAs单量子威尔斯和（CuAlSe_2/CuGaSe_2）_m超晶格。PL测试表明，由于Ga和Al的相互扩散，在CuAlSe_2/CuGaSe_2界面形成了Cu（Al，Ga）Se_2合金层，层厚小于200埃的超晶格在600 ℃的生长温度下合金化最多，550 ℃的低生长温度有利于减少互扩散，实现超晶格的形成.用半经验紧束缚方法计算了CuAlSe_2/CuGaSe_2和CuAlSe_2/ZnSe超晶格的能带结构。在CuAlSe_2/CuGaSe_2超晶格中，当层厚小于200埃时，禁带宽度增加，而在CuAlSe_2/ZnSe超晶格中，禁带宽度增加到250 meV，其中CuAlSe_2和ZnSe的禁带宽度均为2.67 eV。少

Epitaxial layrs of CuGaSe_2 and CuAlSe_2 and the CuGaSe_2/CuAlSe_2 superlattice have been grown by the metalorganic molecular beam epitaxy (MOMBE) and the molecular beam epitaxy (MBE).1. MOMBE The c-axis-oriented epitaxial layrs of CuGaSe_2 and CuAlSe_2 have been grown on the GaAs (100) substrate. Based on the X-ray diffraction photoluminescence (PL), the modulation reflectance and Raman methods, the epilayrs are found to be of good quality. The CuAlSe_2/CuGaSe_2/GaAs heterostructure and the superlattice of the layr thickness of 200A have been prepared. However, the XPS in-depth profile did not reflect the periodicity of the superlattice. This suggests that the flatness of the layr is not so good and the improvement of the surface morphology is required.2. MBE Epilayrs of CuGaSe_2 and CuAlSe_2 have been grown on the GaAs (100) substrate with the RHEED in situ measurement. The epilayrs with flat surface have been realized by trimming the Cu/III ratio and by decreasing the growth rate. T … More he CuAlSe_2/CuGaSe_2/CuAlSe_2/GaAs single quantum wells and the (CuAlSe_2/CuGaSe_2)_m superlattices have been prepared. PL measurements indicated that the alloyed layr of Cu (Al, Ga) Se_2 has been formed at the CuAlSe_2/CuGaSe_2 interface due to the interdiffusion of Ga and Al. Therefore, superlattices with layr thickness less than 200A are mostly alloyed at the growth temperature of 600C.The low growth temperature of 550C has proven to be useful in order to reduce the interdiffusion to realize superlattice formation.3. Band calculation of superlattice Energy band structures of CuAlSe_2/CuGaSe_2 and CuAlSe_2/ZnSe superlattices have been calculated by the semi-empirical tight-binding method. Increase of the bandgap energy has been found for the CuAlSe_2/CuGaSe_2 superlattice with layr thickness of less than 200A.Increase of the bandgap energy up to 250 meV has been found CuAlSe_2/ZnSe superlattice in which the both CuAlSe_2 and ZnSe have bandgap energy of 2.67 eV.The new band engineering for obtaining the large bandgap semiconductor has been suggested using the CuAlSe_2/ZnSe superlattice. Less