Subband dependent mobilities and carrier saturation mechanisms in thin Si doping layers in GaAs in the high density limit

Skuras, E.; Kumar, Ranjan; Williams, Robin L.; Strading, R A; Dmochowski, J. E.; Johnson, E. A.; MacKinnon, A.; Harris, J. J.; Beall, R B; Skierbeszewski, C; Singleton, John; Wel, P.J. van der; Wiśniewski, P.

doi:10.1088/0268-1242/6/6/023

Cited by 88 publications

(32 citation statements)

References 15 publications

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“…The thickness of the δ-layer is used as an adjustable parameter in the calculations and amounts to 160 Å and 340Å for samples N2 and N7, respectively. This value is rather large compared to typical values for Si δ-layers [23][24][25] (20-100 Å), and is due to the large ability of Sn to segregate [4]. Another mechanism, which might result in a relatively large width, is the repulsive interaction between the ionised impurities [26].…”

Section: Analysis and Discussionmentioning

confidence: 82%

Sn delta-doping in GaAs

Kulbachinskii

Кытин

Lunin

et al. 1999

Semicond. Sci. Technol.

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We have prepared a number of GaAs structures δ-doped by Sn using the well known molecular beam epitaxy growth technique. The samples obtained for a wide range of Sn doping densities were characterized by magnetotransport experiments at low temperatures and in high magnetic fields up to 38 T. Hall-effect and Shubnikov-de Haas measurements show that the electron densities reached are higher than for other δ-dopants, like Si and Be. The maximum carrier density determined by the Hall effect equals 8.4 × 10 13 cm −2 . For all samples several Shubnikov-de Haas frequencies were observed, indicating the population of multiple subbands. The depopulation fields of the subbands were determined by measuring the magnetoresistance with the magnetic field in the plane of the δ-layer. The experimental results are in good agreement with selfconsistent bandstructure calculations. This calculation shows that in the sample with the highest electron density also the conduction band at the L point is populated.

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Section: Analysis and Discussionmentioning

confidence: 82%

Sn delta-doping in GaAs

Kulbachinskii

Кытин

Lunin

et al. 1999

Semicond. Sci. Technol.

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“…Several calculations of electron mobilities, excluding DX centers and assuming the measured free-electron concentration equal to the doping density, have been performed for ␦-doped GaAs structures, and reasonable agreement was obtained with the experimental findings. 3,4 However, the quantum mobilities measured by Skuras et al 5 in ␦-doped GaAs structures with a very high doping density (1.1ϫ10 13 cm Ϫ2 ) in the presence of an external hydrostatic pressure up to 20 kbar cannot be explained by the existing theory described in Refs. 3 and 4 due to population of DX centers.…”

Section: Introductionmentioning

confidence: 87%

Electron mobility in Si δ-doped GaAs with spatial correlationsin the distribution of charged impurities

et al. 1997

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We present a theoretical study of electron mobility in heavily Si ␦-doped GaAs in the presence of applied hydrostatic pressure. At low temperature the electron-ionized impurity scattering is the most important scattering mechanism. The presence of DX centers in Si-doped GaAs results in spatial correlations of the charged impurities, which increase the electron mobility through the structure factor of the charged-impurity distribution and/or a decrease in the density of the charged dopants. A Monte Carlo approach has been developed to simulate this distribution in two dimensions for the d ϩ /DX 0 and d ϩ /DX Ϫ models. In the mobility calculation, both intrasubband and intersubband scatterings are considered with the electron-electron screening within the random-phase approximation. A detailed comparison between experiment and theory shows that theory excluding the correlation effects underestimates the electron mobility systematically. In cooperation with other mechanisms, e.g., self-compensation of Si dopants, in the ␦ layer, both DX-center models can explain the experimental results well. This indicates that in order to effectively study the electronic properties of DX centers via the electron mobility in ␦-doped structures, the samples must have a relatively low doping concentration in order to prevent self-compensation. ͓S0163-1829͑97͒08616-5͔

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“…Therefore, an increase in the electron density of all occupied subbands should be observed after illumination as the DX centers revert to singly ionized shallow donor states. 13,14 In contrast, electron trapping states not connected to Si but distributed uniformly throughout the InAlAs will pin E F in a manner similar to background acceptors. [15][16][17][18] Such states will cause preferential removal of free electrons from the higher subbands of the ␦-doped region; this is the observed response for the In 0.52 Al 0.48 As samples discussed here.…”

Section: CMmentioning

confidence: 99%

Shubnikov–de Haas effect and persistent photoconductivity in In0.52Al0.48As

Skuras

Stanley

Long

et al. 1999

Journal of Applied Physics

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The Shubnikov-de Haas effect in InAlAs measured using pulsed magnetic fields up to 50 T is reported. The InAlAs samples were grown by molecular beam epitaxy ͑MBE͒ and were either ␦ or slab doped with silicon at densities up to 7ϫ10 12 cm Ϫ2 . Comparison of experimental subband densities with those calculated self-consistently shows that spreading of Si occurs by surface segregation at growth temperatures of ϳ520°C, similar to its behavior in MBE-grown InGaAs. In contrast to InGaAs, the InAlAs exhibits persistent photoconductivity which appears to be caused by a bulk defect rather than DX͑Si͒ states. © 1999 American Institute of Physics. ͓S0021-8979͑99͒00423-5͔Shubnikov-de Haas ͑SdH͒ measurements combined with self-consistent calculations ͑SCC͒ have been used to estimate the spreading of Si as a function of growth temperature in ␦-and slab-doped InGaAs.1-3 However, the larger electron effective mass in InAlAs and its lower electron mobility mean that substantially higher magnetic fields are required to resolve the individual subbands for structures doped with comparable donor densities. In this communication, we report the observation of the SdH effect in InAlAs ␦ and slab doped with Si to densities of N Si ϳ7ϫ10 12 cm Ϫ2 . Pulsed magnetic fields up to 50 T were needed to measure peaks due to depopulation of the Landau levels of the iϭ0 subband. A comparison of the SdH data with SCC provides an estimate of Si spreading at growth temperatures T S around 520°C. Persistent photoconductivity ͑PPC͒ due to deep states in the InAlAs has been observed, and evidence is presented which rules against DX͑Si͒ centers as the cause.The Si ␦-and slab-doped InAlAs layers were grown lattice matched on Fe-InP͑100͒ by molecular beam epitaxy ͑MBE͒ in a constant As 2 flux of Ϸ2.0ϫ10 15 molecules cm Ϫ2 s Ϫ1. The growth rate was 1.0 m/h and the growth temperature was varied between T S Ϸ460 and 520°C. A series of 0.5-2.0 m thick InGaAs layers doped uniformly with Si at concentrations ranging from 5ϫ10 16 to 4ϫ10 A 100 Å cap layer of un-InGaAs was grown to assist the formation of ohmic contacts on Hall bars with a 3:1 length to width ratio. The quantum transport measurements were carried out at 4.2 K with a 0-50 T pulsed magnetic field system 4 and at 1.2 K in a 0-13 T superconducting magnet. The electron subband densities n i ϭ2e i /h (iϭ0,1,2,...) were calculated from the peaks in the fast Fourier transform ͑FFT͒ spectra of the SdH data assuming, unresolved spin splitting. i is the magnetic frequency of the ith peak, e is the electron charge, and h is Planck's constant. For the PPC study, the samples were cooled to 4.2 K in the dark, illuminated with a red light emitting diode ͑LED͒ until the zero magnetic field longitudinal resistance stopped increasing, and then measured 1 and 14 h after illumination.Two representative samples, B689 and A1337, have been selected to illustrate the new data. B689 was grown entirely at T S ϳ520°C and was ␦ doped with N Si ϭ7ϫ10 12 cm Ϫ2 . A1337 was ␦ doped to ϳ5ϫ10 12 cm Ϫ2 and was also grown at 520°C,...

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Subband dependent mobilities and carrier saturation mechanisms in thin Si doping layers in GaAs in the high density limit

Cited by 88 publications

References 15 publications

Sn delta-doping in GaAs

Sn delta-doping in GaAs

Electron mobility in Si δ-doped GaAs with spatial correlationsin the distribution of charged impurities

Shubnikov–de Haas effect and persistent photoconductivity in In0.52Al0.48As

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