Aynı koşullar altında üretilen Au/p-TlInS2/n-InP pseudo Schottky eklemlerin karakteristik parametrelerinin istatistiksel incelenmesi

Abstract

Au/p-TlInS2/n-InP Psödo-Schottky (PS) eklemleri, ön yüzüne omik kontak yapılmış n-InP altlığın arka yüzeyine altın (Au) doğrultucu kontak imalatından önce ince p-TlInS2 inversiyon tabakası büyütülerek üretildi. Metal-yarı iletken arayüzeyinin kararlılığı için ardışık tavlama işlemi uygulandı. Azot gazı atmosferinde 200 oC'de 5 dakika süreli ardışık ikinci tavlama işleminden sonra engel yüksekliğinde (EY) yaklaşık 0,260 eV’luk bir artış gözlemlendi. Aynı şartlarda üretilmiş (18 nokta) Au/p-TlInS2/n-InP PS eklemlerinin EY, idealite faktörü (n) ve seri direnc (Rs) parametreleri Termiyonik Emisyon (TE) teorisi kullanılarak oda sıcaklığı ve karanlıkta ölçülmüş akım-voltaj (I-V) ve kapasite-voltaj (C-V) karakteristiklerinden hesaplandı. I-V ve C-V karakteristiklerinden hesaplanan EY sırasıyla (0.620-0.844) eV ve (0.669-0.973) eV, idealite faktörü n (1.023-1.706) ve Rs seri direnç değerleri ise (28.3-131) Ω aralığında değişim sergilemektedir. Aynı koşullar altında hazırlanmalarına rağmen PS eklemlerin karakteristik parametreleri kendileri arasında farklılık gösterdiğinden, eklem parametreleri üzerinde Tung modeli kullanılarak istatistiksel bir çalışma yapıldı. Gauss fonksiyonu ile fit edilen EY, n ve Rs verilerinin ortalama değerleri sırasıyla ϕ ̄_(I-V)=(0.7⁡5 5 〖±0.0〗⁡5 9) eV, ϕ ̄_(C-V)=(0.8⁡0 3 〖±0.〗⁡0 78) eV, n =(〖1.〗⁡3 84 〖±0.〗⁡1 52) andR_s=(88.4 ±⁡2 8.0)Ω olarak elde edildi. Au/p-TlInS2/n-InP PS eklemi için yanal homojen EY (ϕ_(hom.)), n_(imf.)=1.006 ve Δϕ_(imf.)=18.0 meV değerleri kullanılarak ϕ_(eff.) "- n" çiziminden ϕ_(hom.)=0.800 eV olarak elde edilmiştir. C-V ölçümlerinden elde edilen ortalama EY değeri ϕ_(hom.) ile oldukça uyum içindedir. Parametrelerdeki bu uyum, Au/p-TlInS2/n-InP PS ekleminde gözlenen EY inhomojenliğinin Tung tarafından ileri sürülen EY'nin uzaysal dağılımı hipotezi dikkate alınarak açıklanabileceğini gösterir.

Keywords

• n-InP
• p-TlInS2
• pseudo Schottky eklem
• I-V and C-V ölçümü
• engel inhomojenliği
• Tung modeli

Statistical investigation of characteristic parameters for Au/p-TlInS2/n-InP pseudo Schottky junctions produced under the same conditions

Abstract

Pseudo-Schottky junctions (PSJs) on moderately doped (MD) n-InP were fabricated by introducing a thin p-TlInS2 counter layer before the assembly of gold rectifying contact. Successively annealing treatment was applied to create a stable inversion layer at the metal-semiconductor (MS) interface. PSJs were made with a significant barrier height (BH) enhancement, typically by the value of 0.260 eV for gold Schottky gate, after the second annealing process at 200 oC in a nitrogen atmosphere for 5 minutes. Junction parameters such as BH, ideality factor (n) and serial resistance (Rs) of identically fabricated (18 dots) Au/p-TlInS2/n-InP PSJs have been computed by thermionic emission (TE) theory from current-voltage (I-V) and capacitance-voltage (C-V) characteristics, at room temperature and in the dark. BHs derived from I-V and C-V characteristics varied from 0.620 to 0.844 eV and 0.669 to 0.973 eV, respectively. In addition, the values of n varied from 1.023 to 1.706 and the serial resistances Rs varied from 28.3 to 131 Ω. Since all parameters of PSJs differ from one junction to another, even if they are prepared under the same conditions, a statistical study was made on the junction parameters using Tung’s model. The mean values of the experimental BH, the ideality factor, and the series resistance data, which were fitted by the Gaussian function, were found to be ϕ ̄_(I-V)=(0.7⁡5 5 〖±0.0〗⁡5 9) eV, ϕ ̄_(C-V)=(0.8⁡0 3 〖±0.〗⁡0 78) eV, n =(〖1.〗⁡3 84 〖±0.〗⁡1 52) and〖 R〗_s=(88.4 ±⁡2 8.0)Ω, respectively. The lateral homogeneous BH (ϕ_(hom.)) value of 0.800 eV for the Au/p-TlInS2/n-InP junctions has been obtained from the ϕ_(eff.) "- n" plot by using n_(imf.)=1.00⁡6 and Δϕ_(imf.)=18.0 meV It has been seen that the mean BH obtained from the C-V measurements correlates well with the value of ϕ_(hom.). The good agreement in these parameters indicates that the BH inhomogeneity observed in the Au/p-TlInS2/n-InP PJ can be described by considering the spatial distribution hypothesis of BH put forward by Tung.

Keywords

• n-InP
• p-TlInS2
• pseudo-Schottky junction
• I-V and C-V measurement
• barrier inhomogeneities
• Tung’s model

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