Passivation of GaN surface by chemical bath deposition of thin CdS layers

Ewa Papis 1Eliana Kaminska 1Anna Piotrowska 1Renata Kruszka 1Norbert Kwietniewski 1Witold Rzodkiewicz 1Andrzej Wawro 2

1. Institute of Electron Technology (ITE), al. Lotników 32/46, Warszawa 02-668, Poland
2. Polish Academy of Sciences, Institute of Physics, al. Lotników 32/46, Warszawa 02-668, Poland


GaN and related semiconductor compounds are important materials for optoelectronic and electronic applications, especially in high-temperature, high-power and high-efficiency systems. In order to exploit the full potential of these materials more effective methods of surface passivation are highly required. The standard methods of surface passivation of GaN-based devices rely on the use of silicon oxides or nitrides SiO2, Si3N4 and SiON. Several sulphur passivation processes including chemical treatments in (NH4)2S, Na2S and CH3CSNH2 aqueous or alcoholic solutions have been proposed without definitive achievements. On the other hand, chemical bath deposited CdS films have been proven useful to passivation of III-V semiconductors surfaces [1].

In this paper we present the results on passivation of GaN surface using Chemical Bath Deposition (CBD) technique, forming CdS thin layers. 0.1M SC(NH2)2 as sulphur source, 0.1M CdSO4 as source of Cd and 2.4M NH4OH as solution for hydrolysis were used in the experiments. Variable Angle Spectroscopic Ellipsometry (VASE) was chosen to provide information of thickness, refractive index and dielectric function of passivating layers. Surface morphology was examined by optical microscopy with phase contrast and by Atomic Force Microscopy (AFM). To study the influence of CBD - CdS passivation on electronic properties on GaN surface, Ir/p GaN Schottky diodes were prepared on passivated and nonpassivated GaN samples. The results show, that Chemical Both Deposition from 0.1M SC(NH2)2 - 0.1M CdSO4 ammonia solution enables to form thin (d = 20nm) CdS films, with good insulating properties (ε2 = 0.0003 at E = 1.1eV) and smooth surface (rms = 1.2nm). Increasing of height of Ir/p GaN barrier from 0.56 to 0.81 indicates that CdS layer deposited by Chemical Bath Deposition techniques enhanced performance of Schottky barrier.

Part of the research was supported by the grant from the EC HYPHEN Contract Number: FP6-027455.

[1]. O. Vigil-Galan, J. Vidal Larramendi, I. Riech, G. Pena Rodriguez, A. Iribarren, J. Aguilar-Hernandez, G. Contreras-Puente, Semicond. Sci. Technol. 17, 1193, 2002.

Related papers
  1. Structural aspects of nanoscale magnetic patterning of epitaxial metallic thin films
  2. Application of Ti-Al-N MAX-phase for contacts to GaN
  3. Transparent p-type ZnO obtained by Ag doping
  4. Methods of stress investigations in dielectric layer of MIS structures
  5. Photothermal investigations of SiC thermal properties
  6. Characterization of Ir and IrO2 Schottky contacts on n-type 4H-SiC under high temperature stress
  7. Determination of stress in composite engineered substrates for GaN-based RF power devices
  8. Optimisation of electrochemical sulphur treatment of GaSb and related semiconductors: application to surface passivation of GaSb/In(Al)GaAsSb TPV cells
  9. Comparison of various GaSb-based device structures for application in thermophotovoltaic cells
  10. Optical properties of p-type ZnO:(N, As, Sb)
  11. Optical and magnetooptical properties of the p-type ZnMnO.
  12. Relationship between condition of deposition and properties of W-Ti-N thin films prepared by reactive magnetron sputtering
  13. Structural analysis of reactively sputtered W-Ti-N thin films
  14. Phase relationships in annealed Cu-Al-O layers
  15. TaSiN, TiSiN and TiWN diffusion barriers for metallization systems to GaN
  16. Transparent Conducting Oxides as Ohmic Contacts for GaSb-based Thermophotovoltaic Cells
  18. Thermally stable Ru-Si-O gate electrode for AlGaN/GaN HEMT
  19. Preparation and characterization of hexagonal MnTe and ZnO layers
  20. p-type conducting ZnO: fabrication and characterisation
  21. Diffusion barrier properties of reactively sputtered W-Ti-N thin films
  22. Study of Long-Term Stability of Ohmic Contacts to GaN
  23. Fabrication of GaSb microlenses by photo and e-beam lithography and dry etching

Presentation: Poster at Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth, by Ewa Papis
See On-line Journal of Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth

Submitted: 2007-01-16 14:21
Revised:   2009-06-07 00:44
© 1998-2018 pielaszek research, all rights reserved Powered by the Conference Engine