The structure of the MOS QDIP. The 20-layer SiGe quantum dots were formed by ultrahigh vacuum chemical vapor deposition, and the doping was introduced in the Si spacer. The inset shows the TEM photograph of SiGe quantum dots.
Spectral response of the -spacer sample at 0 and . The inset shows the response at shorter wavelength, indicating cutoff wavelength at at and at .
The schematic energy levels in quantum dots under different biases. The band is not flat at since the flatband voltage is negative.
The photoluminescence (PL) spectrum of the -spacer sample at . The band edge of the SiGe dot signal corresponding to HH1 to conduction band in SiGe dot is .
Two possible mechanisms responsible for the hole supply. (a) Electrons in the valence band jump into the conduction band via interface states and tunnel into the gate electrode through the thin oxide, and the holes are left in the valence band. (b) Holes tunnel from the gate electrode to Si.
Comparison of the spectral responses of the -spacer sample, the -QD sample, and the sample at (at bias). Both the -spacer sample and the sample have a long-wavelength transition.
The schematic detection of long-wavelength infrared inside the -doping layer. The long-wavelength infrared photoexcited carriers can be collected in the -spacer sample and sample. No absorption around is observed in the -QD sample, since the valence band barrier of SiGe QD is too large to block the photoexcited hole from the -doping well.
The detectivity of the -spacer sample at different temperatures. The detection has a peak at , and the detection has a peak at .
Dark current of the -spacer sample at . The detector is operated at inversion bias.
Condition of three different samples.
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