Structural properties of GaAs/Ge heterostructures as a function of growth conditions

Lazzarini, L.; Li, Y.; Franzosi, P.; Giling, L.J.; Nasi, L.; Longo, F.; Urchulutegui, M.; Salviati, G.

doi:10.1016/0921-5107(94)90115-5

Cited by 15 publications

(3 citation statements)

References 7 publications

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“…[18][19][20][21][22][23][24][25] Domains of different sublattice locations are separated by AP boundaries ͑APBs͒, which are expected to provide deep levels inside the forbidden band and to act as scattering centers. 26,27 The problem of the formation of misfit dislocations ͑MDs͒, due to the difference in lattice constant between GaAs and Ge, 28,29 affects solar cell performance, i.e., it decreases in the minority carrier lifetime, increases in the interface recombination velocity, and increases the leakage at the junction, therefore worsening cell performance. 30,31 One important problem is that Ge atoms easily evaporate from Ge substrates during growth and can be incorporated into the epilayer as n-type impurities during growth of the solar cells ͑this is called the autodoping effect 32,33 ͒.…”

Section: Introductionmentioning

confidence: 99%

Growth, optical, and electron transport studies across isotype n-GaAs/n-Ge heterojunctions

Hudait

Krupanidhi

1999

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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A diode structure consisting of a polar epilayer on a nonpolar substrate grown by metalorganic vapor phase epitaxy often faces problems of antiphase domain formation in the polar semiconductor and cross diffusion across the heterointerface. Ge outdiffusion into GaAs epilayers was studied by low temperature photoluminescence spectroscopy after etching the film from the surface. The absence of p-n junction formation inside the Ge substrate from interdiffusion of Ga and As has been studied by current-voltage characteristics using mesa diodes. These observations were confirmed by electrochemical capacitance voltage polaron profiler and secondary ion mass spectroscopy techniques. To understand the material quality and current conduction mechanism across the GaAs/ Ge heterojunction, I-V characteristics of Si-doped n-GaAs/n-Ge isotype heterojunctions using Au Schottky diodes have been studied for different doping densities. A plethora of growth conditions appear in the literature concerning the attempt to grow antiphase domain ͑APD͒-free GaAs on Ge. In the present case, even though the growth temperature regime is close to reported values, the main difference in minimizing APD formation may arise from the growth rates ͑ϳ3 m/h͒ and the V/III ratio ͑ϳ88͒.

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Section: Introductionmentioning

confidence: 99%

Growth, optical, and electron transport studies across isotype n-GaAs/n-Ge heterojunctions

Hudait

Krupanidhi

1999

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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“…A diode structure consisting of Au/n-GaAs over Ge often gives a higher ideality factor, lower barrier height, and a soft breakdown voltage due to the misfit dislocations formed inside the GaAs substrate during the heteroepitaxial growth process [1]. Unless the MOVPE growth parameters are precisely controlled, the epi-GaAs over Ge often gives antiphase domains and misfit dislocations, which gives rise to poor electrical transport characteristics [2][3][4][5][6][7]. In fact, the grown GaAs epilayer over Ge might contribute to the high density of surface states, which increases the surface recombination velocity, decreases the minority carrier lifetime, and increases the leakage at the junction, all of which worsening the GaAs/Ge solar cell performance [6,7].…”

Section: Introductionmentioning

confidence: 99%

Interface states density distribution in Au/n-GaAs Schottky diodes on n-Ge and n-GaAs substrates

Hudait

Krupanidhi

2001

Materials Science and Engineering: B

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The current-voltage (I -V) and capacitance-voltage (C-V) characteristics of Au/n-GaAs Schottky diodes on n-Ge substrates are investigated and compared with characteristics of diodes on GaAs substrates. The diodes show the non-ideal behavior of I-V characteristics with an ideality factor of 1.13 and barrier height of 0.735 eV. The forward bias saturation current was found to be large (3 ×10 − 10 A vs. 4.32 × 10 − 12 A) in the GaAs/Ge Schottky diodes compared with the GaAs/GaAs diodes. The energy distribution of interface states was determined from the forward bias I -V characteristics by taking into account the bias dependence of the effective barrier height, though it is small. The interface states density was found to be large in the Au/n-GaAs/n-Ge structure compared with the Au/n-GaAs/n + -GaAs structure. The possible explanation for the increase in the interface states density in the former structure was highlighted.

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“…There are however some crystallographic differences between both materials, which require an adequate buffer layer in order to obtain decent material quality [3][4][5][6][7]. half of the price for a 100mm wafer).…”

Section: Introductionmentioning

confidence: 99%

<title>4-mW microcavity LED at 650 nm on germanium substrates</title>

D'Hondt¹,

Modak²,

Delbeke³

et al. 2000

SPIE Proceedings

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We report on the realisation of red micro cavity LED's on germanium substrates, offering a significant cost advantage compared to GaAs wafers. The MCLED structure, grown by LP-MOVPE, consists of 3 GaInP quantum wells within a (detuned) l-X AlGaInP cavity, enclosed by A195GaAs/A155GaAs DBR's, with a current spreading layer on top. MCLED's with a 2OOj.m aperture, exhibit a quantum efficiency up to 4.35% (at lOniA) and an optical power higher than 4mW (at 8OmA), without any packaging. The optical spectrum was centered at 650nm, with a FWHM of Because of the detuning the opening angle ofthese structures was as much as 120°. Rudimentary packaging resulted in a luminous intensity of 2.5cd at 3OmA, with an opening angle of Initially the electrical performance was not optimal, but additional tests and a new processing have indicated that forward biases as low as 2.OV (at 2OmA) can be obtained for LED's on Gesubstrates. The new processing further resulted in an improved optical output with 5mW at 8OmA. We feel there is room for further improvement, but already we have demonstrated the feasibility of germanium substrates for commercial red (to orange/yellow) LED applications.

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Structural properties of GaAs/Ge heterostructures as a function of growth conditions

Cited by 15 publications

References 7 publications

Growth, optical, and electron transport studies across isotype n-GaAs/n-Ge heterojunctions

Growth, optical, and electron transport studies across isotype n-GaAs/n-Ge heterojunctions

Interface states density distribution in Au/n-GaAs Schottky diodes on n-Ge and n-GaAs substrates

<title>4-mW microcavity LED at 650 nm on germanium substrates</title>

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