Simulation of electron escape from GaNAs/GaAs quantum well solar cells

Abstract

Quantum wells embedded in the active region of single-bandgap solar cells have previously been shown to increase the absorption of photons of energies lower than the host bandgap, while maintaining the open-circuit voltage. Fast carrier escape from the quantum wells is essential to achieve such performance enhancements. In the present work, we use ensemble Monte Carlo simulation to model the escape time for photo-excited carriers in dilute nitride GaNAs/GaAs quantum wells to the continuum, for different well structures. The simulated electron escape rate due to polar optical phonon absorption and emission decreases exponentially with the well depth in agreement with thermionic emission theory.Index Terms -ensemble Monte Carlo, carrier escape, quantum well,photovoltaic cells.

Research on photo-generated carriers escape in PIN and NIN structures with quantum wells

“…This was explained as being due to thermionic emission 15) and tunneling processes 16) after relaxation. The special MQWs in a PIN structure can be used in solar cells 17,18) and photodetectors. 19,20) However, if the PIN structure is replaced with a NIN structure with bias, then the photo-generated carriers cannot escape from the MQWs.…”

Analysis of Photo-Generated Carrier Escape in Multiple Quantum Wells

“…We have investigated a large number of low dimensional material systems, including GaN/InGaN quantum well structures [21], GaAs/InGaAs quantum well structures [20], and GaAs/InAs quantum dot (QD) structures [29], all of which indicate that, when the thickness of the MQWs structure region is less than 100 nm, more than 85% of carriers can escape by comparing their integral strength of the PL peak under the OC and SC states. This special structure can be used to make new types of optoelectronic devices, such as quantum well solar cells and photodetectors (IQWIP) [25,30], which widen the range of applications of quantum wells. Meanwhile, as for the NIN structure that the MQW structures are placed into in the depletion region of the NN junction (NIN structure), there is no obvious fluorescence quenching phenomenon in the case of SC, even if bias voltage is applied [21,22,31].…”