Point-contact measurements for high-resolution profiling of high-resistivity III - V semiconductors

Siegel, W.; Kühnel, G.; Niklas, J. R.; Jurisch, M.; Hoffman, Benjamin C.

doi:10.1088/0268-1242/11/6/002

Cited by 16 publications

(4 citation statements)

References 12 publications

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“…Mesoscopic resistivity mappings with comparable lateral resolution can be achieved by PCT [2]. We have implemented this technique and corroborated its reliability by direct comparison with measurements of the Bergakademie Freiberg group [3] and with COREMA measurements.…”

Section: B Experimental Detailsmentioning

confidence: 66%

High resolution EL2 and resistivity topography of SI GaAs wafers

Wickert

Stibal²,

Hiesinger³

et al. 1998

Semiconducting and Insulating Materials 1998. Proceedings of the 10th Conference on Semiconducting and Insulating Materials (SI

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The mesoscopic inhomogeneity of LEC grown semi-insulating (SI) GaAs wafers has been investigated with EL2' absorption topography (EAT), photoluminescence topography (PLT), point contact topography (PCT) and contactless resistivity mapping (COREMA). Significant progress with respect to sensitivity of EAT and lateral resolution of COREMA has been achieved. High resolution topograms of wafers cut from ingots subject to standard and modified annealing procedures are presented. Direct comparison of EL2' and resistivity topograms reveals significant differences in the mesoscopic contrast and a contrast reversal for modified annealing. These observations can be explained very satisfactorily by assuming mesoscopic inhomogeneity of the intrinsic acceptor concentration which is modified during annealing. A model involving generation of Ga vacancies by dissolution of As,, antisites and gettering of the interstitial As at precipitates is presented and discussed. A. IntroductionThe macro-and mesoscopic homogeneity of liquid-encapsulated Czochralski (LEC) SI GaAs wafers has been improved in recent years by systematic optimization of ingot annealing processes. But mesoscopic fluctuations of resistivity, related to the cellular distribution of dislocations, continue to stimulate research-and application-oriented investigations, requiring topographic optical and electrical characterization techniques with high sensitivity and lateral resolution. PLT has been widely used for qualitative homogeneity assessment, although the correlation between PL intensity and resistivity appears to be incidental and often is not observed at all. Hence, high resolution, high sensitivity topograms of the resistivity itself (obtained with PCT and COREMA) and of the EL2 concentration (obtained with EAT) are needed. Evaluation of these topograms not only qualifies the material, but also allows elucidating details in the defect redistributions and the resulting changes of the compensation processes. B. Experimental DetailsThe EL2' absorption topography [l] has been enhanced in sensitivity to obtain precise mapping of concentration variations down to 1% with a lateral resolution of 30 pm. Mesoscopic resistivity mappings with comparable lateral resolution can be achieved by PCT [2]. We have implemented this technique and corroborated its reliability by direct comparison with measurements of the Bergakademie Freiberg group [3] and with COREMA measurements. The non-contacting resistivity technique COREMA [4] thus far offered a lateral resolution of about 2.5 mm, insufficient for mesoscopic investigations. We have achieved an improvement of three orders of magnitude by designing a 80 pm diameter capacitive probe with upgraded measurement circuitry. Using the same step size of 30 pm as PCT, the topograms can be directly compared. For large cell structures in the mm range, the relative variation of conductivity is comparable for PCT and p-COREMA. As will be shown below, mesosocopic variations on a smaller scale encountered in LEC grown material are somewhat u...

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Section: B Experimental Detailsmentioning

confidence: 66%

High resolution EL2 and resistivity topography of SI GaAs wafers

Wickert

Stibal²,

Hiesinger³

et al. 1998

Semiconducting and Insulating Materials 1998. Proceedings of the 10th Conference on Semiconducting and Insulating Materials (SI

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“…Samples of this region show strong mesoscopic electrical nonuniformities detected by point contact measurements. 10 Samples with carrier concentration in the region 10 9 Ϭ 10 10 cm Ϫ3 had values of the thermal activation energy between 0.62 and 0.67 eV. Such values can principally be caused by several reasons.…”

Section: Enhancement Of the Hall Mobility In Undoped Gaas With Low Camentioning

confidence: 99%

Enhancement of the Hall mobility in undoped GaAs with low carrier concentration by light excitation

Kažukauskas

Kühnel

Siegel

1997

Applied Physics Letters

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“…However, only in a few papers 4,7 were these electrical nonuniformities explicitly brought in connection with the cellular structure of dislocations, which is the main source of nonuniformities in undoped bulk-grown GaAs. 7,8 Model calculations using a standard effective medium theory which take into account these cellular-structure related nonuniformities were performed recently by the authors. 9 The results agree well with the characteristic H (n) dependence found experimentally.…”

Section: Introductionmentioning

confidence: 99%