Minority carrier diffusion, defects, and localization in InGaAsN, with 2% nitrogen

Kurtz, S. R.; Allerman, Andrew A.; Seager, C. H.; Sieg, R. M.; Jones, E. D.

doi:10.1063/1.126989

Cited by 155 publications

(81 citation statements)

References 17 publications

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“…The same conclusion results if we consider the number of N atoms, N W , in a window of fixed size, and move that window over the alloy layer; we find fluctuations in the values of N W which equal, within a few %, the expected value of 18 ≈ where is the average value of NW [15]. Thus, we find no evidence for medium-or long-range compositional fluctuations of the N atoms, as has been suggested in some recent studies [4,7]. To model GaAsN alloys, at least of the type grown here, our results indicate that one can simply assume a modest ( %) enhancement of the number of second (and possibly also the first) nearest-neighbor pairs, together with a random distribution of all other pairs.…”

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confidence: 49%

“…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.…”

Section: Introductionmentioning

confidence: 99%

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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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confidence: 49%

Section: Introductionmentioning

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 mobility of GaN x As 1-x films ranges typically from about ten to a few hundred cm 2 /Vs. 52,53 These values are over an order of magnitude smaller than the electron mobility in GaAs at comparable doping levels. Figure 9 shows the change in roomtemperature mobility of Ga 0.93 In 0.07 N 0.017 As 0.983 :Si with the free electron concentration.…”

Section: Decrease Of Electron Mobilitymentioning

confidence: 84%

“…These include a reduction of the fundamental band-gap energy, 1,2 a significant increase in electron effective mass and a decrease in electron mobility. [3][4][5] Furthermore, a new optical transition (E + ) above the fundamental band gap energy has been observed. 6,7 As one quantitative example, the incorporation of only one percent of nitrogen into GaAs induces a strikingly large reduction of 0.18 eV in the fundamental band-gap energy.…”

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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“…1,2 The most extensively studied HMAs to date are III-N-V alloy systems. It has been found that the substitution of the group V element in group III-V compounds with small amounts of nitrogen leads to dramatic changes of the electronic properties, resulting in a reduction of the fundamental band-gap energy as opposed to the increase predicted by the VCA, 3,4 significant increase in electron effective mass and decrease in electron mobility, [5][6][7] and the appearance of a new optical transition (E + ) from the valence band to the conduction band at the Γ point. 8,9 As one quantitative example, the incorporation only one percent of nitrogen into GaAs can induce a strikingly large reduction of 0.18 eV in the fundamental band-gap energy.…”

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confidence: 99%

Effect of oxygen on the electronic band structure in ZnOxSe1−x alloys

Shan

Walukiewicz

Ager

et al. 2003

Applied Physics Letters

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The effect of alloying small amounts of ZnO with ZnSe on the electronic band structure has been studied. Optical transitions in MBE-grown ZnO x Se 1-x epitaxial films (0 < x < 1.35%) were investigated using photoreflectance and photoluminescence spectroscopies. The fundamental band-gap energy of the alloys was found to decrease at a rate of about 0.1 eV per atomic percent of oxygen. The pressure dependence of the band gap was also found to be strongly affected by the O incorporation. Both the effects can be quantitatively explained by an anticrossing interaction between the extended states of the conduction band of ZnSe and the highly localized oxygen states located at approximately 0.22 eV above the conduction band edge.

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Minority carrier diffusion, defects, and localization in InGaAsN, with 2% nitrogen

Cited by 155 publications

References 17 publications

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

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

Band anticrossing in dilute nitrides

Effect of oxygen on the electronic band structure in ZnOxSe1−x alloys

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