Impact of Temperature and Doping on the Performance of ${{\bf Ge}}/{{\bf G}}{{{\bf e}}_{1 - {\boldsymbol{x}}}}{{\bf S}}{{{\bf n}}_{\boldsymbol{x}}}/{{\bf Ge}}$ Heterojunction Phototransistors

Abstract

We study the effect of temperature and doping in Si-based GeSn heterojunction phototransistors (HPTs) for low-power-consuming, low-cost, and high-speed mid-infrared (MIR) applications. The incorporation of Ge 1−x Sn x alloy in the base of our HPTs significantly shortens the emitter-to-collector transit time, leading to high cutoff frequency (f T) due to an increase in mobility. Furthermore, the Ge 1−x Sn x base extends the optical detection over a wide range (up to 2500 nm) due to the shrinkage of the bandgap energy caused by alloying with Sn. Additionally, spectral responsivity increases with Sn alloying due to the increased absorption coefficient. Our results show that f T and responsivity are strongly dependent not only on doping but also on temperature. The impact of temperature on the noise behavior of phototransistors was also analyzed for frequencies up to 100 GHz. As the temperature increased, the signal-to-noise ratio (SNR) decreased; however, spectral responsivity significantly improved. The high SNR, responsivity, and f T values of the GeSn HPT make it a potential candidate for future Si-based uncooled high-speed MIR photodetection.

Design of tensile-strained GeSn/SiGeSn structure for low threshold mid-infrared laser application

“…Figure 1 depicts the 3D schematic of Ge 1−x Sn x /Si 1−y−z Ge y Sn z heterostructure laser wrapped with Si 3 N 4 stress liner grown on a Ge/SOI (Silicon On Insulator) substrate through a Ge 1−t Sn t buffer [31]. In order to achieve a fully relaxed lattice-matched Ge 1−x Sn x /Si 1−y−z Ge y Sn z heterostructure, t > x and the thickness of Ge 1−t Sn t higher than a critical value were used to counteract the compressive strain and line defects introduced by the Ge substrate, respectively.…”

Theoretical Investigation of Strain-Adjustable Ge0.92Sn0.08 Light-Emitting Diodes With Giant Magnetostrictive Stressor for Short-Wave Infrared Light Source

“…Then, the active layer is etched into a cylinder with an outer diameter of 3μm. Finally, the metal electrodes are prepared by metal contact deposition with a lift-off process [32,33]. Tb0.3Dy0.7Fe1.95 belongs to the ternary Laves phase with lower magneto crystalline anisotropy and higher magnetostriction coefficient (λ) which can be used as the adjustable stressor [34][35][36].…”

Design of strain-adjustable Si0.1Ge0.78Sn0.12_Ge0.90Sn0.10_Si0.012Ge0.848Sn0.14 double-heterostructure SWIR photodetectors with giant magnetostrictive stressor

“…In the absence of external stress, the magnetostriction coefficient (λ) will increase accordingly by adjusting the strength of the external magnetic field (H) until saturation, up to 1200 ppm [14]. The Si0.1Ge0.78Sn0.12/Ge0.90Sn0.10/Si0.012Ge0.848Sn0.14 is etched with an outer length of 6μm, and the metal electrodes are deposited on the surface by metal contact deposition [15]. An adjustable strain in the range of 0-0.11% can be obtained by adjusting the magnetic field strength as shown in Fig 3.…”