Structural elaboration and external cavity control of semiconductor superlattices with room-temperature terahertz gain

2019 Fiscal Year Final Research Report

• Project/Area Number: 17H03232
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Electronic materials/Electric materials
• Research Institution: Nagaoka University of Technology
• Principal Investigator: Unuma Takeya 長岡技術科学大学, 工学研究科, 准教授 (20456693)
• Co-Investigator(Kenkyū-buntansha): 玉山 泰宏 長岡技術科学大学, 工学研究科, 准教授 (50707312)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 半導体超格子 / テラヘルツ / 光学利得 / 量子ビート / トンネル効果 / 非平衡系

Outline of Final Research Achievements

For biased semiconductor superlattices (SLs) composed of GaAs-based materials, the spatial shape and distribution of electron wavefunctions dependent on their internal structures were found to be significant factors in the characteristics of terahertz gain versus temperature and bias electric field. In particular, this insight allowed us to quantitatively understand the spectral linewidth of terahertz gain originating from Bloch oscillations in an isolated SL miniband and also the phase shift of Bloch oscillations in the presence of strong interminiband interaction. In addition, we designed a metal-based metamaterial serving as both a planar electrode and an external cavity and introduced it into SL samples.

Free Research Field

半導体物性

Academic Significance and Societal Importance of the Research Achievements

異なる半導体材料をナノレベルの厚さで周期的に積層させた半導体超格子について，室温でテラヘルツ電磁波の利得（増幅作用）があることに着目し，内部構造と外部構造の工夫によって利得を操るための新たな物理を提示した。電波と光の中間にあたるテラヘルツ電磁波の小型固体光源は様々な応用へ期待されているものの未だ発展途上にあるため，室温動作と周波数可変性を両立できる人工積層構造の長所を発展させたことに本研究の意義がある。