Abstract
We report a detailed characterization of a Ge/Si0.16Ge0.84multiple quantum well (MQW) structure on Ge-on-Si virtual substrate (VS) grown by ultrahigh vacuum chemical vapor deposition by using temperature-dependent photoreflectance (PR) in the temperature range from 10 to 300 K. The PR spectra revealed a wide range of optical transitions from the MQW region as well as transitions corresponding to the light-hole and heavy-hole splitting energies of Ge-on-Si VS. A detailed comparison of PR spectral line shape fits and theoretical calculation led to the identification of various quantum-confined interband transitions. The temperature-dependent PR spectra of Ge/Si0.16Ge0.84MQW were analyzed using Varshni and Bose-Einstein expressions. The parameters that describe the temperature variations of various quantum-confined interband transition energies were evaluated and discussed.
Highlights
Semiconductor quantum well heterostructures have been implemented in many commercial optoelectronic devices
These results showed that Ge/SiGe multiple quantum well (MQW) can be a promising candidate for efficient light emitting devices for Si-based photonic circuits
The experimental PR spectra were fitted with the first-derivative Lorentzian line shape (FDLL) function
Summary
Semiconductor quantum well heterostructures have been implemented in many commercial optoelectronic devices. The electroluminescence properties of the material system emitting in 1.55 μm region for optical telecommunication have been reported [10, 11] These results showed that Ge/SiGe MQW can be a promising candidate for efficient light emitting devices for Si-based photonic circuits. Previous study reported tensile strained Ge/SiGe MQW [13], which may be exploited to cover the range of wavelengths used in telecommunications and for longer wavelength applications in health care and pollution monitoring devices [14]. A detailed investigation of the material system may provide useful information for crystal growers, so that optimal growth conditions can be set to fabricate desirable tensile strained Ge/SiGe MQW. We present a detailed study of a Ge/ Si0.16Ge0.84 MQW structure grown on Ge-on-Si VS by temperature-dependent PR measurements in the range between 10 and 300 K. For temperature-dependent measurement, a closed-cycle cryogenic refrigerator equipped with a digital thermometer controller with temperature stability better than 0.5 K was used
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