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

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。通过X射线衍射光致发光(PL)、调制反射光谱和拉曼光谱等测试手段对外延层进行了表征，发现外延层质量良好。制备了CuAlSe_2/CuGaSe_2/GaAs异质结和层厚为200A的超晶格。然而，XPS的深度剖面并没有反映出超晶格的周期性。这说明涂层的平整度不是很好，表面形貌有待改善。用RHEED原位测量方法在GaAs(100)衬底上生长了CuGaSe_2和CuAlSe_2分子束外延。通过调整Cu/III比和降低生长速率，实现了表面平坦的外延层。T…制备了较多的He-CuAlSe_2/CuGaSe_2/CuAlSe_2/GaAs单量子阱和(CuAlSe_2/CuGaSe_2)_m超晶格。PL测量表明，由于Ga和Al的互扩散，在CuAlSe_2/CuGaSe_2界面形成了合金化层Cu(Al，Ga)Se_2。因此，Layr厚度小于200A的超晶格大多在600℃的生长温度下合金化，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。发现层厚小于200a的CuAlSe_2/CuGaSe_2超晶格的带隙能量增加，最高可达250 meV，其中CuAlSe_2和ZnSe的带隙能均为2.67 eV。提出了利用CuAlSe_2/ZnSe超晶格获得大禁带半导体的新的能带工程方法。较少

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