Effect of a SiO 2 Anti-reflection Layer on the Optoelectronic Properties of Germanium Metal-semiconductor-metal Photodetectors

• Published in: Journal of semiconductor technology and science Vol. 17; no. 4; pp. 483 - 491
• Main Authors: Zumuukhorol, Munkhsaikhan, Khurelbaatar, Zagarzusem, Kim, Jong-Hee, Shim, Kyu-Hwan, Lee, Sung-Nam, Leem, See-Jong, Choi, Chel-Jong
• Format: Journal Article
• Language: Korean
• Published: 2017
• Subjects: anti-reflection layer; responsivity; Ge; SiO_2; MSM photodetector
• ISSN: 1598-1657

The interdigitated germanium (Ge) meta-lsemiconductor-metal (MSM) photodetectors (PDs) with and without an $SiO_2$ anti-reflection (AR) layer was fabricated, and the effect of $SiO_2$ AR layer on their optoelectronic response properties were investigated in detail. The lowest reflectance of 15.6% at the wavelength of 1550 nm was obtained with a $SiO_2$ AR layer with a thickness of 260 nm, which was in a good agreement with theoretically calculated film thickness for minimizing the reflection of Ge surface. The Ge MSM PD with 260 nm-thick $SiO_2$ AR layer exhibited enhanced device performance with the maximum values of responsivity of 0.65 A/W, the quantum efficiency of 52.2%, and the detectivity of $2.49{\times}10^9cm\;Hz^{0.5}W^{-1}$ under the light illumination with a wavelength of 1550 nm. Moreover, time-dependent switching analysis of Ge MSM PD with 260 nm- thick $SiO_2$ AR layer showed highest on/off ratio with excellent stability and reproducibility. All this investigation implies that 260 nm-thick $SiO_2$ AR layer, which is effective in the reduction in the reflection of Ge surface, has a great potential for Ge based optoelectronic devices.