A carrier escape study from InP/InGaAs single quantum well solar cells

Abstract

Carrier escape from InP/AlGaAs single quantum well structures is studied by means of simultaneous steady state photocurrent and photoluminescence measurements. The activation energy for escape is measured for the first time in this system. The photoluminescence from the InGaAs wells indicates that a significant number of carriers do not escape at room temperature thus affecting the temperature dependence of the cell. An estimate of the nonradiative efficiency of the device studied is given as a function of bias and temperature. The relevance to new applications is discussed.

Quantum wells in photovoltaic cells

“…More recent QWC designs have employed a p-i-n structure [3] with the QWs located in the intrinsic region; a schematic bandgap diagram is shown in figure 1.1. The carriers escape from the QWs thermally and by tunnelling [4,5,6].…”

“…QWCs based on InP are of interest for solar as well as for thermophotovoltaic (TPV) applications. First, material combinations such as InP/InGaAs were investigated [30,31,32,6], which was then extended to quaternary material (lattice-matched to InP) InP/In 1−x Ga x As y P 1−y (x = 0.47y) [33,34,35].…”

Carriers escape mechanisms in shallow InGaAs/GaAs quantum wells grown on vicinal (001) GaAs substrates

“…The understanding of this mechanism is important for device engineering, since devices normally operate at room temperature, where the PL quenching is more important. Some studies in this direction have already been reported on InGaAs/GaAs [1], InGaAs/GaAlAs [2] and InP/InGaAs [3] structures, but only on nominal substrates. When vicinal substrates are considered, other confinement potentials appear which affect the escape mechanisms.…”

“…However, due to the small confinement energy of the carriers in this type of structure (shallow QW), thermal quenching of the intrinsic photoluminesence (PL) is often observed [1][2][3]. The quenching of the PL intensity of the main excitonic emission is associated with the carriers' escape from the well to the barrier.…”

Quantum wells in photovoltaic cells

“…First, material combinations such as InP/InGaAs were investigated [30,31,32,6], which was then extended to quaternary material (lattice-matched to InP) InP/In 1−x Ga x As y P 1−y (x = 0.47y) [33,34,35].…”