研究目的
Investigating the intersubband transition engineering in the conduction band of asymmetric coupled Ge/SiGe quantum wells for the development of silicon-based THz quantum cascade lasers.
研究成果
The study demonstrates the effective tuneability of the design of the energy of ISB transitions and the spatial overlap of the excited electronic wavefunctions in n-type Ge/SiGe ACQWs. The high structural/interface quality and control over subband hybridization are promising for the development of electrically pumped light-emitting devices.
研究不足
The study is limited by the challenges of epitaxial integration of Ge-rich structures on Si wafers, including growth optimization and accurate determination of band offsets from THz spectroscopy experiments.
1：Experimental Design and Method Selection
The study combines structural and spectroscopic experiments on 20-module superstructures, each featuring two Ge wells coupled through a Ge-rich SiGe tunnel barrier. The methodology includes THz spectroscopic data comparison with numerical calculations of intersubband optical absorption resonances.
2：Sample Selection and Data Sources
Samples were grown by ultra-high vacuum CVD, featuring a wide and a narrow Ge well of varying thicknesses, separated by a SiGe tunnel barrier. The samples were characterized using STEM, XRD, and SIMS.
3：List of Experimental Equipment and Materials
FEI Titan microscope for STEM, Rigaku SmartLab tool for XRD, CAMECA IMS Wf Tool for D-SIMS, Bruker Vertex 70 v for FTIR spectroscopy.
4：Experimental Procedures and Operational Workflow
The samples were grown at 500°C using germane and silane. Structural characterization was performed using STEM and XRD. Optical absorption spectra were measured at T = 10 K by FTIR spectroscopy.
5：Data Analysis Methods
Data analysis involved comparing THz spectroscopic data with numerical calculations of intersubband optical absorption resonances, using a Schr?dinger–Poisson solver for simulations.
独家科研数据包，助您复现前沿成果，加速创新突破
获取完整内容
