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The Pt/Au Schottky contacts to InGaN samples with different background carrier concentrations are fabricated. The crystal qualities of InGaN samples are characterized by X-ray diffraction (XRD) and atomic force microscope (AFM), and the correlation between threading dislocation density of InGaN and growth temperature is further clarified. The full width at half maximum (FWHM) values of the InGaN (0002) XRD rocking curves show that the density of threading dislocations in InGaN, which can seriously deteriorate InGaN crystal quality and surface morphology, decreases rapidly with increasing growth temperature. The Hall measurements show that the background carrier concentration of InGaN increases by two orders of magnitude as growth temperature decreases from 750 to 700℃, which is due to a reduced ammonia decomposition efficiency leading to the presence of high-density donor-type nitrogen vacancy (VN) defects at lower temperature. Therefore, combining the studies of XRD, AFM and Hall, it can be concluded that the higher growth temperature is favorable for realizing the InGaN film with low density of VN defects and threading dislocations for fabricating high-quality Schottky contacts, and then the barrier characteristics and current transport mechanism of Pt/Au/n-InGaN Schottky contact are investigated by current-voltage measurements and theory analysis based on the thermionic emission (TE) model and thermionic field emission (TFE) model. The results show that Schottky characteristics for InGaN with different carrier concentrations manifest obvious differences. It is noted that the high carrier concentration leads to the Schottky barrier height and the ideality factor obtained by TE model are quite different from that by TFE model due to the presence of high density of VN defects. This discrepancy suggests that the VN defects lead to the formation of the tunneling current and further reduced Schottky barrier height. Consequently, the presence of tunneling current results in the increasing of total transport current, which means that the defects-assisted tunneling transport and TE constitute the current transport mechanism in the Schottky. However, the fitted results obtained by TE and TFE models are almost identical for the InGaN with lower carrier concentration, indicating that TE is the dominant current transport mechanism. The above studies prove that the Pt/Au/n-InGaN Schottky contact fabricated using low background carrier concentration shows better Schottky characteristics. Thus, the properly designed growth parameters can effectively suppress defects-assisted tunneling transport, which is crucial to fabricating high-quality Schottky devices.
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Keywords:
- InGaN /
- X-ray diffraction spectrum /
- Schottky barrier /
- thermionic emission
[1] Green M A, Emer Y K, Hishikaw A Y, Warta W, Dunlop E D 2013 Prog. Photovolta 21 1
[2] Piprek J, Römer F, Witzigmann B 2015 Appl. Phys. Lett. 106 101101
[3] Aseev P, Rodriguez P, Gómez V J, Alvi N, Mánuel J M, Morales F M, Jiménez J J, García R, Senichev A, Lienau C, Calleja E, Nötzel R 2015 Appl. Phys. Lett. 106 072102
[4] Tang F, Zhu T, Oehler F, Fu W Y, Griffiths J T, Massabuau F C P, Kappers M J, Martin T L, Bagot P A J, Moody M P, Oliver R A 2015 Appl. Phys. Lett. 106 072104
[5] O'donnell K P, Fernandez-Torrente I, Edwards P R, Martinet R 2004 J. Cryst. Growth 269 100
[6] Davydov V Y, Klochikhin A A, Emtsev V V, Kurdyukov D, Ivanov S V, Vekshin V A, Bechstedt F, Furthmller J, Aderhold J, Graul J, Mudryi A V, Harima H, Akihiro H, Yamamoto A, Haller E E 2002 Phys. Status Solidi 234 787
[7] Li Y, Huang Y R, Lai Y H 2009 IEEE J. Sel. Top. Quant. 15 1128
[8] Fabien M, Doolittle W A 2014 Sol. Energ Mat. Sol. C. 130 354
[9] Yamamoto A, Sugita K, Bhuiyan A G, Hashimoto A, Narita N 2013 Materials for Renewable and Sustainable Energy 2 1
[10] Li Y, Chen H, Chen K J 2011 IEEE Electron Dev. Lett. 32 303
[11] Lin Y S, Ma K J, Yang C C, Weirich T E 2003 J. Mater. Sci-Mater. El. 14 49
[12] Li S X, Yu K M, WU J, Jones R E, Walukiewicz W, Agerlll J W, Shan W, Haller E E, Lu H, Schaff W J 2005 Phys. Rev. B. 71 161201R
[13] Jang J S, Kim D, Seong T Y 2006 J. Appl. Phys. 99 073704
[14] Lin Y J, Lin W X, Lee C T, Hang H C 2006 JPN J. Appl. Phys. 45 2505
[15] Wang X F, Shao Z G, Chen D J, Lu H, Zhang R, Zhen Y D 2014 Chin. Phys. Lett. 31 057303
[16] Vegard L 1921 Physics 5 17
[17] Wuu D, Wu H, Chen S, Tsai T, Zheng X, Horng R 2009 J. Cryst. Growth. 311 3063
[18] Oliver R A, Kappers M J, Humphreys C J, Briggs G A D 2005 J. Appl. Phys. 97 013707
[19] Liu W, Soh C B, Chen P, Chua S J 2004 J. Cryst. Growth. 268 509
[20] Soh C B, Liu W, Chua S J, Tripathy S, Chi D Z 2004 J. Cryst. Growth. 268 478
[21] Lee C R, Noh S K, Leem J Y, Son S J, Lee I H 1997 J. Cryst. Growth. 182 11
[22] Mira S, Collazo R, Dalmau R, Sitar Z 2007 Phys. Stat. Sol. 4 2260
[23] Wu X H, Elsass C R, Abare A, Mack M, Keller S, Petroff P M, DenBaars S P, Speck J S, Rosner S J 1998 Appl. Phys. Lett. 72 692
[24] Yu L S, XING Q J, Qiao D J, Lau S S, Redwing J, LIU Q Z 1998 J. Appl. Phys. 84 2099
[25] Tsao C C, Wang Y, Weiner J, Bagnato V S 1996 J. Appl. Phys. 80 8
[26] Morkoç H 1999 Nitride Semiconductor and Devices (Vol. 1) (New York: Springer-Verlag Berlin Heidelberg) pp196-203
[27] Hashizume T, Kotani J, Hasegawa H 2004 Appl. Phys. Lett. 84 4884
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[1] Green M A, Emer Y K, Hishikaw A Y, Warta W, Dunlop E D 2013 Prog. Photovolta 21 1
[2] Piprek J, Römer F, Witzigmann B 2015 Appl. Phys. Lett. 106 101101
[3] Aseev P, Rodriguez P, Gómez V J, Alvi N, Mánuel J M, Morales F M, Jiménez J J, García R, Senichev A, Lienau C, Calleja E, Nötzel R 2015 Appl. Phys. Lett. 106 072102
[4] Tang F, Zhu T, Oehler F, Fu W Y, Griffiths J T, Massabuau F C P, Kappers M J, Martin T L, Bagot P A J, Moody M P, Oliver R A 2015 Appl. Phys. Lett. 106 072104
[5] O'donnell K P, Fernandez-Torrente I, Edwards P R, Martinet R 2004 J. Cryst. Growth 269 100
[6] Davydov V Y, Klochikhin A A, Emtsev V V, Kurdyukov D, Ivanov S V, Vekshin V A, Bechstedt F, Furthmller J, Aderhold J, Graul J, Mudryi A V, Harima H, Akihiro H, Yamamoto A, Haller E E 2002 Phys. Status Solidi 234 787
[7] Li Y, Huang Y R, Lai Y H 2009 IEEE J. Sel. Top. Quant. 15 1128
[8] Fabien M, Doolittle W A 2014 Sol. Energ Mat. Sol. C. 130 354
[9] Yamamoto A, Sugita K, Bhuiyan A G, Hashimoto A, Narita N 2013 Materials for Renewable and Sustainable Energy 2 1
[10] Li Y, Chen H, Chen K J 2011 IEEE Electron Dev. Lett. 32 303
[11] Lin Y S, Ma K J, Yang C C, Weirich T E 2003 J. Mater. Sci-Mater. El. 14 49
[12] Li S X, Yu K M, WU J, Jones R E, Walukiewicz W, Agerlll J W, Shan W, Haller E E, Lu H, Schaff W J 2005 Phys. Rev. B. 71 161201R
[13] Jang J S, Kim D, Seong T Y 2006 J. Appl. Phys. 99 073704
[14] Lin Y J, Lin W X, Lee C T, Hang H C 2006 JPN J. Appl. Phys. 45 2505
[15] Wang X F, Shao Z G, Chen D J, Lu H, Zhang R, Zhen Y D 2014 Chin. Phys. Lett. 31 057303
[16] Vegard L 1921 Physics 5 17
[17] Wuu D, Wu H, Chen S, Tsai T, Zheng X, Horng R 2009 J. Cryst. Growth. 311 3063
[18] Oliver R A, Kappers M J, Humphreys C J, Briggs G A D 2005 J. Appl. Phys. 97 013707
[19] Liu W, Soh C B, Chen P, Chua S J 2004 J. Cryst. Growth. 268 509
[20] Soh C B, Liu W, Chua S J, Tripathy S, Chi D Z 2004 J. Cryst. Growth. 268 478
[21] Lee C R, Noh S K, Leem J Y, Son S J, Lee I H 1997 J. Cryst. Growth. 182 11
[22] Mira S, Collazo R, Dalmau R, Sitar Z 2007 Phys. Stat. Sol. 4 2260
[23] Wu X H, Elsass C R, Abare A, Mack M, Keller S, Petroff P M, DenBaars S P, Speck J S, Rosner S J 1998 Appl. Phys. Lett. 72 692
[24] Yu L S, XING Q J, Qiao D J, Lau S S, Redwing J, LIU Q Z 1998 J. Appl. Phys. 84 2099
[25] Tsao C C, Wang Y, Weiner J, Bagnato V S 1996 J. Appl. Phys. 80 8
[26] Morkoç H 1999 Nitride Semiconductor and Devices (Vol. 1) (New York: Springer-Verlag Berlin Heidelberg) pp196-203
[27] Hashizume T, Kotani J, Hasegawa H 2004 Appl. Phys. Lett. 84 4884
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