TY - JOUR

T1 - Carrier extraction behaviour in type II GaSb/GaAs quantum ring solar cells

AU - Fujita, Hiromi

AU - James Asirvatham, Juanita

AU - Carrington, Peter

AU - Marshall, Andrew

AU - Krier, Anthony

AU - Wagener, Magnus C.

AU - Botha, Johannes Reinhardt

PY - 2014/3

Y1 - 2014/3

N2 - The introduction of quantum dot (QD) or quantum ring (QR) nanostructures into GaAs single-junction solar cells has shown enhanced photo-response above the GaAs absorption edge, because of sub-bandgap photon absorption. However, to further improve solar cell performance a better understanding of the mechanisms of photogenerated carrier extraction from QDs and QRs is needed. In this work we have used a direct excitation technique to study type II GaSb/GaAs quantum ring solar cells using a 1064 nm infrared laser, which enables us to excite electron-hole pairs directly within the GaSb QRs without exciting the GaAs host material. Temperature and laser intensity dependence of the current-voltage characteristics revealed that the thermionic emission process produced the dominant contribution to the photocurrent and accounts for 98.9% of total photocurrent at 0 V and 300 K. Although the tunnelling process gives only a low contribution to the photocurrent, an enhancement of the tunnelling current was clearly observed when an external electric field was applied.

AB - The introduction of quantum dot (QD) or quantum ring (QR) nanostructures into GaAs single-junction solar cells has shown enhanced photo-response above the GaAs absorption edge, because of sub-bandgap photon absorption. However, to further improve solar cell performance a better understanding of the mechanisms of photogenerated carrier extraction from QDs and QRs is needed. In this work we have used a direct excitation technique to study type II GaSb/GaAs quantum ring solar cells using a 1064 nm infrared laser, which enables us to excite electron-hole pairs directly within the GaSb QRs without exciting the GaAs host material. Temperature and laser intensity dependence of the current-voltage characteristics revealed that the thermionic emission process produced the dominant contribution to the photocurrent and accounts for 98.9% of total photocurrent at 0 V and 300 K. Although the tunnelling process gives only a low contribution to the photocurrent, an enhancement of the tunnelling current was clearly observed when an external electric field was applied.

U2 - 10.1088/0268-1242/29/3/035014

DO - 10.1088/0268-1242/29/3/035014

M3 - Journal article

VL - 29

JO - Semiconductor Science and Technology

JF - Semiconductor Science and Technology

SN - 0268-1242

IS - 3

M1 - 035014

ER -