Investigation of Electrical Properties of GaSe:Ge/Te and GaSe:Ge/Ag Schottky Junctions

Abstract

In this paper, we have investigated electrical properties of germanium doped Gallium Selenide (GaSe) single crystals. Germanium doped GaSe single crystals were grown by conventional Bridgman method. Shchottky junctions were obtained by melting Te or Ag elements on the GaSe:Ge surface. In contacts have been made for the electrical measurements. Characteristic properties of Schottky junctions were investigated as functions of temperature and electric field. It was observed that the ratio of forward bias and reverse bias currents in the Schottky junctions varied with both applied electric field and light excitations. Schottky junctions showed asymmetric current-voltage (I-V) characteristics. The light sensitivity of In/GaSe:Ge/Ag/In Schottky junction was found to be higher than that of In/GaSe:Ge/Te/In Schottky junction. The barrier heights of In/GaSe:Ge/Te/In and In/GaSe:Ge/Ag/In Schottky junctions were calculated as 52.92 meV and 41.82 meV, respevtively. Barrier heights of both Schottky junctions decreased with applied electric field. It was found that barrier heights of the Schottky junctions decreased with the square root of the applied electric field as  while the current increased exponentially with the square root of the applied electric field as . These results are consistent with the Frenkel thermoelectric field theory.

Keywords

• Barrier height,gallium selenide,schottky junctions.

GASE:GE/TE VE GASE:GE/AG SCHOTTKY EKLEMLERİNİN ELEKTRİKSEL ÖZELLİKLERİNİN ARAŞTIRILMASI

Abstract

Bu çalışmada, germanyum katkılı Galyum Selenit (GaSe) tek kristallerinin elektriksel özellikleri araştırıldı. Germanyum katkılı GaSe tek kristalleri geleneksel Bridgman metodu ile büyütüldü. Schottky eklemleri GaSe:Ge yüzeyleri üzerine Te ve Ag elementleri eritilerek elde edildi. Elektrik ölçümleri için indiyum kontaklar yapıldı. Schottky eklemlerinin karakteristik özellikleri elektrik alan ve sıcaklığın fonksiyonuna bağlı olarak araştırıldı. Elde edilen Schottky eklemlerinde düz yöndeki akımın ters yöndeki akıma oranının uygulanan elektrik alan ve ışıkla uyarılmaya bağlı olarak değiştiği gözlemlendi. Schottky eklemleri asimetrik akım-gerilim (I-V) karakteristiği gösterdi. In/GaSe:Ge/Ag/In Schottky ekleminin ışık duyarlılığının In/GaSe:Ge/Te/In Schottky ekleminden daha yüksek olduğu bulundu. In/GaSe:Ge/Te/In ve In/GaSe:Ge/Ag/In Schottky eklemlerinin bariyer yükseklikleri sırasıyla 52.92 meV and 41.82 meV olarak hesaplandı. Her iki Schottky ekleminin de bariyer yüksekliği uygulanan elektrik alanla azaldı. Schottky eklemlerinin bariyer yükseklikleri uygulanan elektrik alanın karekökü ile orantılı olarak  gibi küçüldüğü ve akımın uygulanan elektrik alanın karekökü ile gibi üstel olarak değiştiği bulundu. Bu sonuçların Frenkel termoelektrik alan teorisi ile uyumlu olduğu görüldü.

Keywords

• Bariyer yüksekliği,galyum selenit,schottky eklemleri.

References

1. Allakhverdiev K, Baykara T, Ellialtioğlu Ş, Hashimzade F, Huseinova D, Kawamura K, Kaya A A, Kulibekov A M, Onari S, 2006. Lattice vibrations of pure and doped GaSe. Mat. Res. Bull., 41: 751-763.
2. Allers K H, 2004. Prediction of dielectric reliability from I–V characteristics:Poole–Frenkel conduction mechanism leading to pE model for silicon nitride MIM capacitor. Microelectronics Reliability, 44: 411–423.
3. Anis M K, Piercy A R, 1984. Electrical conduction in p-GaSe. J. Phys. D: Appl. Phys., 17: 1229-1232.
4. Augelli V, Manfredotti C, Murri R, Vasanelli L, 1978. Hall-mobility anisotropy in GaSe. Phys. Rev. B, 17: 3221-3226.
5. Bube R H, Lind E L, 1960. Photoconductivity in gallium sulfo-selenide solid solutions. Physical Review, 119: 1535-1537.
6. Capozzi V, 1981. Direct and Indirect Excitonic Emission in GaSe. Phys. Rev. B, 23: 836-840.
7. Capozzi V, 1982. Kinetics of radiative recombinations in GaSe and influence of Cu doping on the luminescence spectra. Phys. Rev. B, 28: 4620-4627.
8. Capozzi V, Minafra A, 1981. Photoluminescence properties of Cu-doped GaSe. J. Phys. C: Solid State Physics, 14: 4335-4346.

9. Fernelius N C, 1994. Properties of gallium selenide single crystal. Progress in Crystal Growth and Characterization of Materials, 28: 243-249.
10. Gasanly N M, Aydınlı A, Salihoğlu Ö, 2001. Thermally stimulated current observation of trapping centers in undoped GaSe layered single crystals. Cryst. Res. Technol., 36: 295-301.
11. Gouskov A, Camassel J, Gouskov L, 1982. Growth and characterization of III-VI layered crystals like GaSe, GaTe, InSe, GaSe1-xTex and GaxIn1-xSe. Prog. Crystal Growth and Charact., 5: 323-413.
12. Gürbulak B, 1997. İkili (InSe:Er, GaSe, GaSe:Gd) ve Üçlü (TlGaSe2, TlGaSe2:Gd) Tek Kristallerinin Büyütülmesi Soğurma ve Elektriksel Özelliklerinin İncelenmesi. Atatürk Üniversitesi Fen Bilimleri Enstitüsü, Doktora Tezi.
13. Harrell W R, Gopalakrishnan C, 2002. Implications of advanced modeling on the observation of Poole–Frenkel effect saturation. Thin Solid Films, 405: 205–217.
14. Kambur H, 2005. Doğal Yalıtkan Tabakalı Al/p-Si Schottky Diyotlarda Elektriksel Karekteristiklerin Frekansa Bağlı Değişimi. Gazi Üniversitesi Fen Bilimleri Enstitüsü, Yüksek Lisans Tezi.
15. Karabulut O, Parlak M, Turan R, Serincan U, Akınoğlu B G, 2006. Influence of ion implantation on structural and photoconductive properties of Bridgman grown GaSe single crystals. Cryst. Res. Technol., 41: 243-249.
16. Karabulut O, Parlak M, Turan R, Serincan U, Tasarkuyu E, Akinoglu B G, 2003. Electrical properties of nitrogen implanted GaSe single crystal. Cryst. Res. Technol., 38: 811-816.
17. Karatay A, Yuksek M, Ertap H, Mak A K, Karabulut M, Elmali A, 2016. Influence of boron concentration on nonlinear absorption and ultrafast dynamics in GaSe crystals. Optical Materials, 64: 74-80.
18. Kim C, Jang K, Kim Y L, 2004. Optical properties of Tm-doped GaSe single crystals. Solid State Communications, 130: 701-704.
19. Lui O K B, Migliorato P, 1997. A new generation-recombination model for device simulation including the poole-frenkel effect and phonon assisted tunnelling. Solid State Electronics, 41: 575-583.
20. Mamedov G M, Karabulut M, Kodolbaş A O, Öktü Ö, 2005. Exciton photoconductivity in Ge doped GaSe crystals. Phys. Stat. Sol. (b), 242: 2885-2891.
21. Manfredotti C, Mancini A M, Murri R, Rizzo A, Vasenelli L, 1977. Electrical properties of p-type GaSe. II Nuovo Cimento, 39: 257-268.
22. Micocci G, Serra A, Tepore A, 1997. Impurity Levels in Sn-Doped GaSe Semiconductor. Phys. Stat. Sol. (a), 162: 649-659.
23. Sanchez-Royo J F, Errandonea D, Segura A, 1998. Tin related double acceptors in gallium selenide sinle crystals. J. Appl. Phys., 83: 4750-4755.
24. Seyhan A, Karabulut O, Akınoğlu B G, Aslan B, Turan R, 2005. Optical Anisotropy in GaSe. Cryst. Res. Technol., 40: 893-895.
25. Shigetomi S, Ikari T, Nakashima H, 2004. Characterization of phosphorus in layered semiconductor GaSe. Journal of Luminescence, 79: 79-84.
26. Shigetomi S, Ikari S, Nakashima H, 2000. Electrical properties of p- and n-GaSe doped with As and Ge. Jpn. J. Appl. Phys., 39: 5083-5084.
27. Shigetomi S, Ikari T, Nakashima H, 1993. Optical and Electrical Properties of p-GaSe doped with Sb. Jpn. J. Appl. Phys., 32: 2731-2734.
28. Shigetomi S, Ikari T, Nakashima H, 1997. Electrical and optical characteristics of the layer semiconductor p-GaSe doped with Ag. Phys. Stat. Sol. (a), 160: 159-164.
29. Taylor R A, Ryan J F, 1987. Time resolved exciton photoluminescence in GaSe and GaTe. J. Phys. C: Solid State Physics, 20: 6175-6187.
30. Yakuphanoglu F, Tugluoglu N, Karadeniz S, 2007. Space charge-limited conduction in Ag/p-Si Schottky diode. Physica B, 392: 188–191.
31. Yuksek M, Karatay A, Ertap H, Elmali A, Karabulut M, 2017. Frequency conversion, nonlinear absorption and carrier of GaSe:B/Er crystals. Optical Materials, 66: 137-141.
32. Zeyrek S, 2005. Al/SiNx/p-Si (100) (MYY) Schottky Diyotların Elektriksel Karekteristiklerinin Düşük Sıcaklıklarda İncelenmesi. Gazi Üniversitesi Fen Bilimleri Enstitüsü, Doktora Tezi.