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In order to overcome the intrinsic difficulties in conventional GaAs/AlGaAs multi-quantum well infrared
photodetectors(QWIPs), such as small photocurrent, big dark current and low response speed, a novel tunneling
compensation QWIPs structure is proposed in this paper. Based on static Boltzmann Equation and Equilibrium Equation,
considering scattering of the ionized impurity and the optical vibration, the transportation process of carriers have been
simulated at low temperature. The device is in anti-bias state when adding bias, each periodic unit's maximum voltage is
about 1.5V. Because of big resistance the intrinsic type AlGaAs have large voltage, which is about 1.3V. When electrons
transport in the depletion region and the N-type GaAs, the transportation time is less than the electron momentum
relaxation time. The scattering mechanisms have not yet occurred, and consequently only the perturbation due to the
electric field is observed. Each carrier is shifted the same amount in the direction of the field. Then, only a rigid shift of
the initial distribution function, proportional to the elapsed time and to the electric field value, will occur. The velocity of
all carriers along the field direction, and in turn the drift velocity, increases linearly with time so that that a high value of
the drift velocity can be achieved. The result show that carriers in the novel structure, which transported ballistically
through the region of quantum well accelerated by the large build-in electric field, have more higher transportation speed
and more longer lifetime relative to the conventional QWIPs structure. Due to empty states of the subband in quantum
well region, which was generated by incident infrared light, will be filled by tunneling mechanism, it should be expected
that the photocurrent would increase with the numbers of quantum wells step by step in the novel structure, otherwise
another characteristic would be expected that the absorb wavelength of the photodetector is tunable by different bias
level.
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