Abstract
The realization of a fully integrated group IV electrically driven laser at room temperature is an essential issue to be solved. We introduced a novel group IV side-emitting laser at a wavelength of 1550 nm based on a 3-layer Ge/Si quantum well (QW). By designing this scheme, we showed that the structural, electronic, and optical properties are excited for lasing at 1550 nm. The preliminary results show that the device can produce a good light spot shape convenient for direct coupling with the waveguide and single-mode light emission. The laser luminous power can reach up to 2.32 mW at a wavelength of 1550 nm with a 300-mA current. Moreover, at room temperature (300 K), the laser can maintain maximum light power and an ideal wavelength (1550 nm). Thus, this study provides a novel approach to reliable, efficient electrically pumped silicon-based lasers.
Highlights
The photonic integrated circuit is an emerging technology that uses a crystalline semiconductor wafer as the platform for the integration of active and passive photonic circuits along with electronic components on a single microchip
The light emission of the transverse electric (TE) mode is primarily due to the transition from conduction band to HH sub-band, whereas that of the transverse magnetic (TM) mode is primarily due to the transition from conduction band to LH sub-band [20]
The band edge energy diagram of our Ge/Si quantum well (QW) under a strain of 0.2% is shown in Figure 3c, obtained using the self-consistent Poisson-Schrodinger solver with deformation potentials
Summary
The photonic integrated circuit is an emerging technology that uses a crystalline semiconductor wafer as the platform for the integration of active and passive photonic circuits along with electronic components on a single microchip. Pure group IV semiconductor materials are compatible with the silicon-based CMOS process; group IV element semiconductors are indirect-bandgap semiconductors, and when used as the active region for a laser, their emission efficiency is very low. Researchers at MIT used ultrahigh-vacuum CVD to obtain a high active carrier concentration in n-type Ge [27] Another particular characteristic of Ge is that the direct bandgap is 0.8 eV, which means that the radiative recombination of the direct band corresponds to a wavelength of 1550 nm, which is the telecom wavelength. We introduced a 0.2% tensile strain into the Ge layers using a lattice thermal mismatch process and 1 × 1019 cm−3 n-type doping using the thermal diffusion process to improve the direct-band radiative recombination in Ge. The results show that the laser exhibits good edge emission characteristics and a large laser emission power at room temperature. It is found that increasing the number of QWs can improve the luminous power of laser, but it will lead to more significant carrier loss and decreased gain
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