Optical absorption coefficient calculations of GaSb/GaAs quantum dots for intermediate band solar cell applications

Abstract

Absorption coefficients of GaSb/GaAs quantum dots (QDs) are calculated by the 8-band strain-dependent k· p method and Fermi’s golden rule. A more realistic but simple approach to model the QD ensemble with wetting layer is described. Effects of the QD size and density, and the GaAs spacer thickness for multi-stacked QDs on absorption characteristics are studied. Absorption spectra of the single QD, single layer of QDs, and multi-stacked QDs are presented and discussed. Interband absorption is found to be more intense than intraband absorption. The calculated absorption spectra are brought into the drift-diffusion model coupled with rate equations to determine the current density-voltage curves of the GaSb/GaAs QD solar cells, which are compared with measured data in literature for validation. The models proposed in this work are capable of predicting the short-circuit current density and open-circuit voltage of real devices, and would have the potential to investigate the impact of doping and position of the QD layers, which is necessary for intermediate band solar cell analysis and design.

The structural, electronic and optical properties of ZnTe/CdSe/GaSb heterotrilayer: first-principles study

“…According to the above parameters, after geometric optimization of bulk ZnTe, CdSe and GaSb, the surface models of ZnTe (111), CdSe (111) and GaSb (100) as shown in figures 1(a)-(c) are established by clear surfaces. The lattice constants are 8.747 Å, 8.786 Å and 8.795 Å, respectively, which are coincide with other theoretical and experimental values [24,26,28]. In general, the main techniques to access monolayer and few-layer structures from layered bulk materials are liquid phase exfoliation [40] and mechanical cleavage [41].…”

“…Since ZnTe exhibits visible light absorption and excellent photoelectric properties, as well as convenient p-type doping, so diverse ZnTe nanodevices for optoelectronic applications have been fabricated successfully [24,25]. GaSb/GaAs can be used as solar cell [26], and GaSb semiconductor can be used as infrared LED [27]. CdSe can be considered as a model system for semiconductor nanomaterials.…”

Quantitative description of carrier dynamics in GaSb/GaAs quantum-ring-with-dot structures

“…Self-assembled GaSb/GaAs nanostructures (NSs) such as quantum dots (QDs) and quantum rings (QRs) exhibit the strong localization of holes [1][2][3] because of their type-II band alignment which holes are only confined in the GaSb NSs, whereas electrons dwell in the GaAs region around the NSs [4][5][6]. This situation reduces the overlap between electron and hole wave functions [5,6], and results in long carrier lifetimes [7,8]. Therefore, the GaSb/GaAs NSs are promising for charge-based memory devices [9,10], infrared photodetectors [11,12], and intermediate band solar cells [13][14][15][16][17][18][19].…”

Disorder effect on intersubband optical absorption of n-type δ-doped quantum well in GaAs

“…The fabrication in high quality of δ-doped layers in the quantum wells (QWs) has been achieved thanks to the continuous progresses in epitaxial growth techniques, such as molecular-beam epitaxy and metal-organic chemical vapor infrared detector, modulators etc.. [3,4,[6][7][8][9]. In particular, the inclusion of δ-doped layers in QWs has a great potential for terahertz (THz) technology.…”

“…For this reason, several studies have focused on the optical properties of δ-doped QWs due to their large potential application for optoelectronic devices. [3,4,[6][7][8][20][21][22][23][24][25][26][27]. For instance, Sari et al [28] investigated the nonlinear optical properties in asymmetric n-type double δ-doped GaAs quantum well.…”