Room-temperature direct band-gap electroluminescence from germanium (111)-fin light-emitting diodes

Kazuki Tani, Shin-ichi Saito, Katsuya Oda, Makoto Miura, Yuki Wakayama, Tadashi Okumura, Toshiyuki Mine, Tatemi Ido
2017 Japanese Journal of Applied Physics  
Germanium (Ge) (111) fins of 320 nm in height were successfully fabricated using a combination of flattening sidewalls of a silicon (Si) fin structure by anisotropic wet etching with tetramethylammonium hydroxide, formation of thin Ge fins by selective Si oxidation in SiGe layers, and enlargement of Ge fins by Ge homogeneous epitaxial growth. The excellent electrical characteristics of Ge(111) fin light-emitting diodes, such as an ideality factor of 1.1 and low dark current density of 7.1 ' 10
more » ... ensity of 7.1 ' 10 %5 A cm %2 at reverse bias of %2 V, indicate their good crystalline quality. A tensile strain of 0.2% in the Ge fins, which originated from the mismatch of the thermal expansion coefficients between Ge and the covering SiO 2 layers, was expected from the room-temperature photoluminescence spectra, and room-temperature electroluminescence corresponding to the direct band-gap transition was observed from the Ge fins.
doi:10.7567/jjap.56.032102 fatcat:gwdkm2focnbanlkqo4svnwubhy