Effect of Porous GaAs Layer Morphology on Pd/porous GaAs Schottky Contact

Authors A.P. Oksanich , S.E. Pritchin , M.G. Kogdas , A.G. Kholod, I.V. Shevchenko

Kremenchuk Mykhailo Ostrogradsky National University, 20, Pershotravneva St., 39600 Kremenchuk, Ukraine

Issue Volume 11, Year 2019, Number 5
Dates Received 27 April 2019; revised manuscript received 25 October 2019; published online 25 October 2019
Citation A.P. Oksanich, S.E. Pritchin, M.G. Kogdas, et al., J. Nano- Electron. Phys. 11 No 5, 05007 (2019)
DOI https://doi.org/10.21272/jnep.11(5).05007
PACS Number(s) 85.30.Hi, 85.40.Xx, 07.07.Df
Keywords Schottky contact (5) , Porous layer, GaAs (20) , Ideality factor (10) .

GaAs:Sn – GaAs:Si samples with a porous layer formed on their surfaces have been explored. The porous layer was formed by electrochemical anodization of the surface of n-GaAs:Si sample in HF:C2H5OH  1:1 under 3 min etching time and etching current variation within the range of 20-80 mA. Schottky AgPd contact across the porous layer was formed by electron-beam evaporation, AgGePd ohmic contacts to n+ GaAs:Sn were formed by electron-beam evaporation followed by annealing. It has been identified that an increase in the anodizing current density leads to an increase in the uneven structure of the porous layer, and when the current density is greater than 60mA/cm2, clusters are formed as a result of fragmentary separation of the porous layer from the substrate. The spectral analysis has proved that PL intensity increases with porosity growth. We believe that this effect is due to the fact that the average size of the micropores and the amount of material remaining in the layer decrease with increasing layer porosity. To identify the influence of the porous layer morphology on the Schottky contact parameters, the I-V characteristics of the structures have been explored. It has been discovered that with increasing layer porosity, the difference in characteristics between the structure without porous GaAs and structures with porous GaAs increases, that results in decreasing direct current and increasing reverse current. This can be explained by the decrease in the porous GaAs layer, and, as a consequence, by the decrease in the charge carrier density.The Schottky barrier height for Pd/porous GaAs with different morphology of the porous layer was calculated. It has been found out that the Schottky barrier height increases from 0.65 to 0.73eV with a porous layer thickness. It has been established that the increase in the porous layer thickness leads to the rise of the ideality factor, which grows from 1.24 to 1.7 with the layer height and results in a deterioration of Schottky contact parameters.

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