Characterization of GaAs/InGaAs quantum wells using photocurrent spectroscopy

Abstract

We report on characterization studies of high quality metal-organic vapor phase epitaxy and molecular beam epitaxy grown GaAs/InGaAs quantum wells, set within p-i-n diodes, to determine the well widths, indium mole fractions, and conduction band offset. We present photocurrent spectra containing a larger number of transitions than revealed in photoluminescence or photoluminescence excitation experiments. The energies of these transitions have been modeled using a theoretical characterization tool known as ‘‘contouring,’’ which is used in this strained system for the first time. This has enabled determination of the conduction band offset in GaAs/InGaAs quantum wells, to a value between 0.62 and 0.64, for a range of indium fractions between 0.155 and 0.23. As a final, additional check on our results, we compare the field dependence of the e1-hh1 exciton transition energy with our theoretical calculations and find good agreement.

Recent results for single‐junction and tandem quantum well solar cells

“…The carriers escape from the QWs with near unity efficiency at room temperature by a process of thermally assisted tunneling. The carrier escape is efficient provided that there is sufficient thermal energy 11, 12 and the transverse electric field is sufficiently strong 13, 14. In most QWSCs at room temperature, the carrier capture and escape processes proceed faster than competing recombination processes 13.…”

Well-width dependence of exciton-phonon scattering inInxGa1−xABorri1, Langbein2, Hvam3 et al. 1999Phys. Rev. B

“…26,27 of 0.7 and other material parameters commonly used in literature. 28 In the calculation, the well width was adjusted within 10% in order to fit the experimentally observed excitonic transitions.…”

Effect of strain relaxation on forward bias dark currents in GaAs/InGaAs multiquantum well p–i–n diodes

“…The structural parameters of the MQW, t w , t b , and x are obtained by a combination of x-ray analysis and a method known as contouring. 9 The i-region thickness, close to the MQW thickness, is confirmed by C -V measurements. The excess strain is also shown in Table I.…”