GaAs yarıiletkeni üzerine iletken polimer kaplanarak oluşturulan yapının elektriksel ve optik özelliklerinin incelenmesi
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Date
2015
Authors
Kırsoy, Ahmet
Journal Title
Journal ISSN
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Publisher
Uludağ Üniversitesi
Abstract
Bu çalışmada n-GaAs yarıiletkeni üzerine P3HT poly(3-hexylthiophene), MEH-PPV poly [2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene] iletken polimerleri, fulleren türevi PCBM [6,6]-phenyl-61C-butric acid methyl ester) ve GO (Graphene oxide) iletken materyalleri kaplanarak Schottky engel diyotları üretilmiştir. Çalışmada kullanılan bu iletken organik materyaller (P3HT, MEH-PPV, PCBM, GO), elektronik dünyasında Schottky diyotlar, organik ledler, transistörler, biyosensörler, fotosensörler, fotovoltaik ve güneş pili uygulamaları gibi çok geniş bir kullanım alanına sahiptir. Üretilen diyotların elektriksel karakteristikleri, akım-voltaj (I-V) ve kapasitans-voltaj (C-V) ölçüm metotları kullanılarak incelenmiştir. Bütün ölçümler oda sıcaklığında gerçekleştirilmiştir. Diyot parametreleri çeşitli yöntemlerle hesaplanarak karşılaştırılmıştır. Polimer kullanarak Au/n-GaAs/Au geleneksel Schottky diyodunun elektriksel özelliklerinin kontrol edilebileceği görülmüştür. Au/n-GaAs/GO/Au diyodunun frekansa bağlı C-V ve G/ω-V ölçümleri oda sıcaklığında 10 kHz-1MHz frekans aralığında gerçekleştirilmiştir. C-V ölçümlerinden artan voltajla birlikte her bir frekans için kapasitansın negatif değerler aldığı gözlenmiştir. Literatürde bu durum negatif kapasitans (NC) olarak bilinir. NC özellikle düşük frekanslarda daha dikkat çekici olup, kapasite değerlerinin mutlak değerinin frekansın düşmesiyle arttığı gözlenmiştir. Seri direnç Rs değerleri de NC'nin gözlendiği yığılma bölgesinde düşük frekanslar için yüksek olup, frekansın artmasıyla düştüğü gözlenmiştir. G/ω-V ölçümlerinden de doğal olarak seri direncin tersine bu bölge için frekansın artmasıyla iletkenlik değerlerinin arttığı gözlenmiştir. Diyodun NC karakteristiği iyonizasyon nedeniyle Fermi seviyesinin altındaki dolu durumlarda meydana gelen ara yüzey yük kaybından kaynaklandığı düşünülebilir. Aynı zamanda NC'ye özellikle düşük frekanslarda meydana gelen polarizasyondaki artış ve yapıya daha fazla taşıyıcı girişi atfedilebilir. Üretilen Au/n-GaAs/GO/Au diyodunun I-V ölçümlerinden ışığa duyarlı olduğu tespit edilmiş olup bu yapının fotosensör olarak kullanılabileceği değerlendirilmektedir.
In this study, Schottky Barrier Diodes have been fabricated by coating P3HT poly(3-hexylthiophene), MEH-PPV poly [2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene] conductive polimers, derivative of fullerene PCBM [6,6]-phenyl-61C-butric acid methyl ester) and GO (Graphene oxide) conductive materials onto n-GaAs semiconductor. These organic conductive materials used in the study have a very broad range of application areas such as Schottky diodes, organic light-emitting-diodes, transistors, biosensors, photosensors, photovoltaic and solar cells. Electrical characteristics of the fabricated diodes have been investigated by using the current-voltage (I-V) and capacitance-voltage (C-V) measurement methods. All measurements were performed at room temperature. The diode parameters calculated by various methods were compared. The electrical properties of the conventional Schottky diode can be controlled by using polymer was observed. Frequency dependent C-V and G/ω-V characteristics of Au/n-GaAs/GO/Au Schottky diode have been measured in the frequency range from 10 kHz to 1MHz at room temperature. Negative capacitance values have been observed with the increasing applied voltage for each frequency from C-V measurements. This is known as negative capacitance (NC) in the literature. NC is more remarkable especially at low frequencies, It was observed that the absolute values of capacities increased with the decrease of frequency. Series resistance values Rs, in the accumulation region where NCs occurred, were observed to be high for low frequencies, and they decreased with increasing frequency. Naturally, contrary to series resistance, it was observed from G/ω-V measurements that the values of G/ω increased with increasing frequency in the same region. The negative capacitance characteristic of the diode can be referred to the loss of interface charges at occupied states below Fermi level due to impact ionization processes. It can also be attributed to an increase in the polarization particularly at low frequencies and the introduction of more carriers in the structure. The produced Au/n-GaAs/GO/Au diode was determined to be sensitive to light from I-V measurements and it is evaluated that this structure would be used as photosensor.
In this study, Schottky Barrier Diodes have been fabricated by coating P3HT poly(3-hexylthiophene), MEH-PPV poly [2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene] conductive polimers, derivative of fullerene PCBM [6,6]-phenyl-61C-butric acid methyl ester) and GO (Graphene oxide) conductive materials onto n-GaAs semiconductor. These organic conductive materials used in the study have a very broad range of application areas such as Schottky diodes, organic light-emitting-diodes, transistors, biosensors, photosensors, photovoltaic and solar cells. Electrical characteristics of the fabricated diodes have been investigated by using the current-voltage (I-V) and capacitance-voltage (C-V) measurement methods. All measurements were performed at room temperature. The diode parameters calculated by various methods were compared. The electrical properties of the conventional Schottky diode can be controlled by using polymer was observed. Frequency dependent C-V and G/ω-V characteristics of Au/n-GaAs/GO/Au Schottky diode have been measured in the frequency range from 10 kHz to 1MHz at room temperature. Negative capacitance values have been observed with the increasing applied voltage for each frequency from C-V measurements. This is known as negative capacitance (NC) in the literature. NC is more remarkable especially at low frequencies, It was observed that the absolute values of capacities increased with the decrease of frequency. Series resistance values Rs, in the accumulation region where NCs occurred, were observed to be high for low frequencies, and they decreased with increasing frequency. Naturally, contrary to series resistance, it was observed from G/ω-V measurements that the values of G/ω increased with increasing frequency in the same region. The negative capacitance characteristic of the diode can be referred to the loss of interface charges at occupied states below Fermi level due to impact ionization processes. It can also be attributed to an increase in the polarization particularly at low frequencies and the introduction of more carriers in the structure. The produced Au/n-GaAs/GO/Au diode was determined to be sensitive to light from I-V measurements and it is evaluated that this structure would be used as photosensor.
Description
Keywords
Schottky engel diyotlar, Seri direnç, İletken polimer, P3HT, MEH-PPV, PCBM, GO, NC, Schottky barrier diodes, Series resistance, Conducting polymer
Citation
Kırsoy, A. (2015). GaAs yarıiletkeni üzerine iletken polimer kaplanarak oluşturulan yapının elektriksel ve optik özelliklerinin incelenmesi. Yayınlanmamış doktora tezi. Uludağ Üniversitesi Fen Bilimleri Enstitüsü.