“…42 Based on this model, Δ opt depends linearly on the fluence of 0.8-eV photons because the addition of an optical escape pathway reduces the mean time carriers spent in traps in either the QD or wetting layer and, therefore, increases the conductivity (therefore, the photocurrent) even for a fixed number of carriers. 30 It is worthwhile to mention here that in a recent work, Asahi et al 45 have reported a saturation of two-step photocurrents. However, unlike the work reported here involving the two-step photoexcitation from valence band to intermediate states and from intermediate states to conduction band, Asahi et al 45 observed the saturation by tuning "two-step" photoexcitation from valance band to conduction band and from intermediate states to conduction band.…”
Section: Carrier Escape Nature and Electric Field Effectmentioning
confidence: 75%
“…30 It is worthwhile to mention here that in a recent work, Asahi et al 45 have reported a saturation of two-step photocurrents. However, unlike the work reported here involving the two-step photoexcitation from valence band to intermediate states and from intermediate states to conduction band, Asahi et al 45 observed the saturation by tuning "two-step" photoexcitation from valance band to conduction band and from intermediate states to conduction band.…”
Section: Carrier Escape Nature and Electric Field Effectmentioning
“…42 Based on this model, Δ opt depends linearly on the fluence of 0.8-eV photons because the addition of an optical escape pathway reduces the mean time carriers spent in traps in either the QD or wetting layer and, therefore, increases the conductivity (therefore, the photocurrent) even for a fixed number of carriers. 30 It is worthwhile to mention here that in a recent work, Asahi et al 45 have reported a saturation of two-step photocurrents. However, unlike the work reported here involving the two-step photoexcitation from valence band to intermediate states and from intermediate states to conduction band, Asahi et al 45 observed the saturation by tuning "two-step" photoexcitation from valance band to conduction band and from intermediate states to conduction band.…”
Section: Carrier Escape Nature and Electric Field Effectmentioning
confidence: 75%
“…30 It is worthwhile to mention here that in a recent work, Asahi et al 45 have reported a saturation of two-step photocurrents. However, unlike the work reported here involving the two-step photoexcitation from valence band to intermediate states and from intermediate states to conduction band, Asahi et al 45 observed the saturation by tuning "two-step" photoexcitation from valance band to conduction band and from intermediate states to conduction band.…”
Section: Carrier Escape Nature and Electric Field Effectmentioning
“…In addition, we have investigated the detailed two-step photocurrent generation as functions of the excitation power in interband and intersubband transitions. The two-step photocurrent exhibited saturation when the interband excitation power increased, and the saturation level depended on the intersubband excitation power 19 . We proposed a model to interpret the observed two-step photocurrent and discussed the dynamics of electrons generated in the DWELL.…”
We studied the dynamics of electrons generated by two-step photoexcitation in an intermediate-band solar cell (IBSC) comprising InAs/GaAs/Al
0.3
Ga
0.7
As dot-in-well (DWELL) structure using time-resolved photocurrent (TRPC) measurement. The examined IBSC exhibited considerably slower photocurrent decay than a conventional InAs/GaAs quantum dot IBSC, which is due to the extraordinarily long-lived electrons in the DWELL. In order to retrieve the electron lifetime from the decay profile, we developed a model reproducing the observed decay and performed parameter fitting. The fitting results indicate that the electron lifetime in the DWELL is approximately 30 μs. In the two-colour excitation TRPC measurement, we found that an additional infrared (IR) light accelerates the photocurrent decay while the photocurrent increases by approximately 3%, because the additional IR light causes two-step photoexcitation of electrons in the DWELLs towards the conduction band. Furthermore, we demonstrated that the open-circuit voltage increases with increasing of the contribution of the second IR excitation process.
“…Note that, in this experiment, we did not use a simulator and, indisputably, there were no artefacts of the simulator’s sensitive reference channel optical detectors with scattered laser light. Furthermore, we did not perform a signal modulation technique for the photocurrent detection, because the lifetime of electrons separated from the holes can be extended to milliseconds 3 .Fig. 1Interband excitation power density dependence of two-step photon up-conversion current at 300 K. a Change in the short-circuit current density (Δ J SC ).…”
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