Improvement of electroluminescence from CdF2/CaF2 intersubband transition light-emitting structure by trench patterning and hydrogen annealing of Si substrate

Abstract

An improvement of the electroluminescence (EL) intensity of the CdF 2 /CaF 2 intersubband transition (ISBT) light-emitting structure is reported. In the ISBT active region, the precise control of crystal growth is strongly required. In this work, the hydrogenannealing surface flattening of Si substrates was employed to obtain a high quality active region to suppress non-radiative leakage current. A markedly flat surface was obtained in the 30-µm-wide trench bottom after hydrogen annealing. In the EL measurement of the device fabricated in the trench, the EL intensity was approximately 40 times stronger than that of the device without patterning and hydrogen annealing.

Room temperature near-infrared electroluminescence of Si/CaF2 quantum cascade laser structures grown on an SOI substrate

“…It was also strongly suggested that layer thickness fluctuation occurs in the interval longer than the coherent length of the horizontal direction of the QW, if not, the multi-peaks should be smeared out. From the viewpoint of morphological study of epitaxial growth of CaF 2 on Si, island formation with an atomically flat plateau can be observed, 35) which is a potential candidate for the explanation of the formation of low fluctuation QWs. However, it should be noted that in order to clarify the detail of EL behavior, further study is necessary that focuses on various factors such as microscopic structural fluctuations or defects, strain, scattering dynamics in QW, or temperature dependence, etc.…”