InGaAsN solar cells with 1.0 eV band gap, lattice matched to GaAs

Kurtz, S. R.; Allerman, Andrew A.; Jones, E. D.; Gee, J.M.; Banaś, J.; Hammons, B. E.

doi:10.1063/1.123105

Cited by 520 publications

(283 citation statements)

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“…[9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] In this article, we show that the effect of nitrogen on the electronic band structure of dilute nitrides can be consistently described in terms of an anti-crossing interaction between localized nitrogen states and the extended conduction-band states of the semiconductor matrix. 6,27 The interaction leads to a significant modification of the band structure of the dilute III-N-V alloys.…”

Section: Introductionmentioning

confidence: 99%

Band anticrossing in dilute nitrides

Shan

Walukiewicz

et al. 2004

J. Phys.: Condens. Matter

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Alloying III-V compounds with small amounts of nitrogen leads to dramatic reduction of the fundamental band-gap energy in the resulting dilute nitride alloys. The effect originates from an anti-crossing interaction between the extended conduction-band states and localized N states.The interaction splits the conduction band into two nonparabolic subbands. The downward shift of the lower conduction subband edge is responsible for the N-induced reduction of the fundamental band-gap energy. The changes in the conduction band structure result in significant increase in electron effective mass and decrease in the electron mobility, and lead to a large enhance of the maximum doping level in GaInNAs doped with group VI donors. In addition, a striking asymmetry in the electrical activation of group IV and group VI donors can be attributed to mutual passivation process through formation of the nearest neighbor group-IV donor nitrogen pairs.

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Section: Introductionmentioning

confidence: 99%

Band anticrossing in dilute nitrides

Shan

Walukiewicz

et al. 2004

J. Phys.: Condens. Matter

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“…The large predicted band gap bowing in this system of highly mismatched anions leads to the possibility of considerable band gap reduction with modest N content [1,2]. Important applications include lasers with wavelength in the 1.3-1.55 µm range, as well as solar cells with band gap around 1.0 eV [3]. Generally speaking the GaAsN and InGaAsN alloys have displayed evidence of inhomogeneities, such as broad photoluminescence (PL) line widths, variable PL decay times, and short minority carrier diffusion lengths [4][5][6][7].…”

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confidence: 99%

Arrangement of nitrogen atoms in GaAsN alloys determined by scanning tunneling microscopy

McKay

Feenstra

Schmidtling

et al. 2001

Applied Physics Letters

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The pair distribution function of nitrogen atoms in GaAs0.983N0.017 has been determined by scanning tunneling microscopy. Nitrogen atoms in the first and third planes relative to the cleaved (1 0) surface are imaged. A modest enhancement in the number of nearest-neighbor pairs particularly with [001] orientation is found, although at larger separations the distribution of N pair separations is found to be random.Considerable interest has developed in recent years concerning GaAsN and InGaAsN alloys with low N content, typically a few %. The large predicted band gap bowing in this system of highly mismatched anions leads to the possibility of considerable band gap reduction with modest N content [1,2]. Important applications include lasers with wavelength in the 1.3-1.55 µm range, as well as solar cells with band gap around 1.0 eV [3]. Generally speaking the GaAsN and InGaAsN alloys have displayed evidence of inhomogeneities, such as broad photoluminescence (PL) line widths, variable PL decay times, and short minority carrier diffusion lengths [4][5][6][7]. Such observations are often taken as an indicator of compositional fluctuations in the materials, although direct structural characterization of such fluctuations is lacking.In this work we use cross-sectional scanning tunneling microscopy (STM) to directly probe the arrangement of N atoms in GaAs 0.983 N 0.017 alloys. Nitrogen atoms of two distinct contrast levels are imaged, which we assign to occupation in the first and third surface planes relative to the (1 0) surface. From an accurate determination of the position of about 1000 N atoms in a continuous strip of alloy material, we compute the distribution function of pair separations. The arrangement of N atoms is found to be quite consistent with that expected from random occupation, with the exception that an enhanced occurrence of nearest-neighbor N pairs is found.The GaAsN alloys studied here were grown on GaAs(001) substrates by metal organic vapor phase epitaxy (MOVPE) at temperatures between 530 and 570 C using TMGa, TBAs or AsH3, and tertiarybutylhydrazine (TBHy) under hydrogen carrier gas. Additional details of the growth and characterization of the material can be found in Ref. [8]. The particular film studied here consists of a GaAs buffer layer followed by a GaAs 0.983 N 0.017 layer, a 52 nm thick GaAs spacer layer, a GaAs 0.972 N 0.028 layer, and a 370 nm thick GaAs cap layer. The thickness of the GaAsN layers was determined by high-resolution x-ray diffraction (HRXRD) to be about 18 nm; STM measurements of their thickness gave results of 14-19 nm depending on location in the wafer. The N contents quoted above were also determined by HRXRD; STM measurements for those quantities gave similar results. The GaAs substrate, buffer layer, and cap layer were doped with Si at a con-1 1°P ublished in Appl. Phys. Lett. 78, 82 (2001).

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“…Ga ͑1−x͒ In x N y As ͑1−y͒ / GaAs heterostructures, in particular, are considered advantageous over InP-based material systems for selected important devices in optical fiber communications. Various devices with attractive performance based on GaInNAs materials have been developed in the ϳ1.3 m wavelength range, [4][5][6][7] and recently there have been substantial advances in the growth of 1.55 m materials. 8 Despite all this progress, growth of high-quality materials is still an important issue.…”

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confidence: 99%