Studing the Effect of Etching Process on the Ohmic Specific Contact Resistance of AlGaN/GaN HEMT
Main Article Content
Abstract
In electronic devices, ranging from integrated circuits to solar cells, the Ohmic specific contact resistance between metal and semiconductor is a measure of device performance. In this paper, the effect of Induction Coupled Plasma etching (ICP) on creating specific contact resistance between metals and semiconductors was investigated by linear transmission method (LTLM). The obtained results show that selecting etching depth and etch process conditions by ICP method before metal coating is a decisive step in the manufacture of low resistance Ohmic contact. The value of formed Ohmic specific contact resistance is the lowest when the etching depth ensures the metal layers to cover the doped AlGaN region at a distance of about 8nm above the AlGaN/GaN interface. With an ion power source (RIE) of 30W and a plasma power source (ICP) of 250W, the etching rate of AlGaN material is approximately 27.21 nm / minute. The Ohmic specific contact resistance of metal layers Ti (20nm) / Al (200nm) / Pd (60nm) / Au (100nm) with AlGaN semiconductor has an optimal value of ρc = 1.08 x 10-7 Ω.cm2, despite the sample was annealing at a relatively low temperature of 650°C in a nitrogen atmosphere.
Keywords
GaN/AlGaN, high-electron mobility transistors (HEMT), Ohmic specific contact resistance, ICP etching process
Article Details
References
[1] Dieter Schroder, Semiconductor metarial and device characterization, 3rd ed., John Wiley & sons, inc., 2006.
[2] S.I.Stepanov et al., Gallium oxide: Properties and application-A review, Rev.Adv.Mater.Sci., vol. 44, pp. 83-86, 2016.
[3] J. K. S.J. Pearton, C.R. Abernathy, M.E. Overberg, G.T. Thaler, A.H. Onstine, B.P. Gila, F. Ren, B. Lou, New applications for Gallium, Mater. today, vol. 5, no. 6, pp. 24-31, June.2006.
[4] D. Jana, S. Porwal, and T. K. Sharma, Confirmation of unintentional donors in AlGaN/GaN HEMT structures by Mg-doping during initial growth of GaN buffer layer, J. Lumin., vol. 219, March 2020.
[5] F. Berthet et al., Characterization and analysis of electrical trap related effects on the reliability of AlGaN/GaN HEMTs, Solid-State Electronics, vol. 72, pp. 15-21, June 2012.
[6] S. Dhakad, N. Sharma, C. Periasamy, and N. Chaturvedi, Optimization of ohmic contacts on thick and thin AlGaN/GaN HEMTs structures, Superlattices Microstructure, vol.111, pp. 922-926, November 2017.
[7] A. Soltani et al., Development and analysis of low resistance ohmic contact to n-AlGaN/GaN HEMT, Diamond Related Materials, vol. 16, no. 2, pp. 262-266, February 2007.
[8] C. Tang, G. Xie, and K. Sheng, Study of the leakage current suppression for hybrid-Schottky/ohmic drain AlGaN/GaN HEMT, Microelectronics Reliability, vol. 55, no. 2, pp 347-351, February 2015.
[9] Q. Feng, L. M. Li, Y. Hao, J. Y. Ni, and J. C. Zhang, The improvement of ohmic contact of Ti/Al/Ni/Au to AlGaN/GaN HEMT by multi-step annealing method, Solid-State Electronics, vol. 53, no. 3, pp. 955-958, September 2009.
[10] A. Taube et al., Temperature-dependent electrical characterization of high-voltage AlGaN/GaN-on-Si HEMTs with Schottky and ohmic drain contacts, Solid-State Electronics, vol. 111, pp-12-17, September 2015.
[11] Y. Liu, M. K. Bera, L. M. Kyaw, G. Q. Lo, and E. F. Chor, Low resistivity Hf / Al / Ni / Au Ohmic Contact Scheme to n-Type GaN, International Journal of Electrical and Computer Engineering, vol. 6, no. 9, pp. 602-605, 2012.
[2] S.I.Stepanov et al., Gallium oxide: Properties and application-A review, Rev.Adv.Mater.Sci., vol. 44, pp. 83-86, 2016.
[3] J. K. S.J. Pearton, C.R. Abernathy, M.E. Overberg, G.T. Thaler, A.H. Onstine, B.P. Gila, F. Ren, B. Lou, New applications for Gallium, Mater. today, vol. 5, no. 6, pp. 24-31, June.2006.
[4] D. Jana, S. Porwal, and T. K. Sharma, Confirmation of unintentional donors in AlGaN/GaN HEMT structures by Mg-doping during initial growth of GaN buffer layer, J. Lumin., vol. 219, March 2020.
[5] F. Berthet et al., Characterization and analysis of electrical trap related effects on the reliability of AlGaN/GaN HEMTs, Solid-State Electronics, vol. 72, pp. 15-21, June 2012.
[6] S. Dhakad, N. Sharma, C. Periasamy, and N. Chaturvedi, Optimization of ohmic contacts on thick and thin AlGaN/GaN HEMTs structures, Superlattices Microstructure, vol.111, pp. 922-926, November 2017.
[7] A. Soltani et al., Development and analysis of low resistance ohmic contact to n-AlGaN/GaN HEMT, Diamond Related Materials, vol. 16, no. 2, pp. 262-266, February 2007.
[8] C. Tang, G. Xie, and K. Sheng, Study of the leakage current suppression for hybrid-Schottky/ohmic drain AlGaN/GaN HEMT, Microelectronics Reliability, vol. 55, no. 2, pp 347-351, February 2015.
[9] Q. Feng, L. M. Li, Y. Hao, J. Y. Ni, and J. C. Zhang, The improvement of ohmic contact of Ti/Al/Ni/Au to AlGaN/GaN HEMT by multi-step annealing method, Solid-State Electronics, vol. 53, no. 3, pp. 955-958, September 2009.
[10] A. Taube et al., Temperature-dependent electrical characterization of high-voltage AlGaN/GaN-on-Si HEMTs with Schottky and ohmic drain contacts, Solid-State Electronics, vol. 111, pp-12-17, September 2015.
[11] Y. Liu, M. K. Bera, L. M. Kyaw, G. Q. Lo, and E. F. Chor, Low resistivity Hf / Al / Ni / Au Ohmic Contact Scheme to n-Type GaN, International Journal of Electrical and Computer Engineering, vol. 6, no. 9, pp. 602-605, 2012.