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Detailed analysis of quasi- ohmic contacts to high resistive GaAs:Cr structures

This study investigates the behavior of quasi-ohmic contacts to GaAs:Cr structures and estimates certain material parameters. The analysis provides a comprehensive understanding of the material and allows for the estimation of n0, Nt, and Et. The results show good agreement between different analyzing methods of I-V curves.

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Detailed analysis of quasi- ohmic contacts to high resistive GaAs:Cr structures

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  1. Detailed analysis of quasi-ohmic contacts to high resistive GaAs:Cr structures A. Lozinskaya, I. Chsherbakov, V. Novikov, O. Tolbanov, A. Tyazhev, A. Zarubin R&D center “Advanced Electronic Technologies” (Functional electronics laboratory) 11th July 2019, Kolympari, Chania, Crete, Greece

  2. Investigate behavior of ohmiccontacts to GaAs:Cr structure • Estimate some parameters of the material Motivation GaAs:Cr wafers of 3`` and 4`` diameter made in Tomsk, Russia • Sensor production • Material testing • and characterization

  3. Resistivity: ~109Ohm×cm Contact’s material: Ni (5nm)/AuGe (150nm)/ Ni (20 nm)/Au (100 nm) Thickness: 250 /500/ 750/ 1000 µm Active area size: ~3×3 mm2 Tested samples GaAs:Cr Top contact 250 500 750 1000 Back contact

  4. Investigated temperature range: 15 - 60°C Accuracy ~ 0,1°C Forward & reverse bias Test conditions Sample Thermostatic oven Voltage control & measurement Current measurement

  5. I-V curves 15°C 25°C 40°C 60°C

  6. Can be Space Charge Limited Current? 60°C (1) Yes, it’s SCLC If U = const,

  7. Space Charge Limited Current [1] Peter, S., 2009. Electrical Characterization of Organic Electronic Materials and Devices, John Wiley and Sons, Ltd., New Jersey, USA.

  8. Space Charge Limited Current IV UT = 0,89 V UTFL = 4,72 V UIV region = 2 UTFL ~10V III II I (2) θ – trap factor I-V characteristic for 250 µm samples @15°C

  9. GaAs:Cr parameters calculation µ0 = 2500 cm2V-1s-1 IV region (m~1,6): ε=ε0εGaAs εGaAs = 13 vsat= 2×107 cm/s θ = 0,29×10-3 I-II region, Ohm-SCLC transition point: n0 = 2,2×106 cm-3 Nt = 1,08×1011 cm-3 III region (m~4): Et-Ec = 0,56 eV

  10. Activation energy Et-Ec=0,56 ±0,08 eV Richardson plot of samples with 500 µm thickness @ 25°C

  11. GaAs:Cr structures with AuGe contacts are described by SCLC transport mechanism; The analysis of structures with quasi-ohmic contacts gives full understanding of material parameters and allows to estimate n0, Ntand Et; Good agreement of the results, obtained by different analyzing methods of I-V curves. Conclusion

  12. Thank you for your attention!Questions? The work was financially supported with grants of RSF # 18-44-06001 (TSU, Russia) and HRSF-0004 (DESY, Germany).

  13. GaAs:Cr parameters calculation Data from Hall measurements Data from IV analysis θ = 6,57×10-5 n0 = 5,03×105 cm-3

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