Publication: Silicon carbide based nanoelectronic and optoelectronic devices for harsh environment applications
Abstract
Nanomalzemeler alanı, Si'ye alternatif olarak geniş bant aralıklı yarı iletkenler üzerine yapılan kapsamlı araştırmalar sayesinde hızla büyümüştür. Nanomalzelerin benzersiz elektriksel ve optoelektronik yetenekleri, bilimsel ve teknolojik açıdan büyük ilgi görmektedir. Artan uygulama alanları çeşitliliği, yenilikçi malzeme sistemleri ve yeni nesil cihaz tasarımlarını zorunlu kılmaktadır. Bunların yüksek hassasiyette çalışma, hızlı tepki verme ve en önemlisi yüksek sıcaklık gibi zorlu çevre şartlarında çalışabilme gibi gereksinimleri karşılaması gerekir. Bu zorlu ortamlar arasında ortaya çıkan aktiviteden en fazla ilgiyi yüksek sıcaklık uygulamaları çekmiştir. Silisyum karbürün (SiC), özellikle 1D ve 2D nanoyapıları, üstün kimyasal ve termal kararlılıkları, yüksek bozunma gerilimi ve yüksek sıcaklıkta yüksek performans elde etme kabiliyeti sağlayan yüksek sürüklenme hızı nedeniyle yüksek sıcaklık uygulamaları için ilgi çekici malzeme haline gelmiştir. Bu tez, yüksek sıcaklıkların SiC ince filmler ve nanotel tabanlı UV fotodedektörler ve alan etkili transistörler üzerindeki etkisini araştırmaya odaklanmaktadır. Yüksek sıcaklığın SiCTF-UVPD'nin (200°C'ye kadar) performans parametreleri üzerindeki etkisi, ve Au nanopartiküller kullanılarak SiCTF-UVPD’nin performans geliştirmesi başarıyla incelendi. Üretilen SiCTF-UVPD 20 V’ luk bir gerilim altında 0.08 pA gibi bir düşük karanlık akım, 0.34 gibi hızlı bir tepki süresi ve 50°C'de 4466 gibi bir yüksek hassasiyet değeri. Son olarak, tek bir silikon karbür nanotelden oluşan bir alan etkili transistör üretilip oda sıcaklığından ve 350°C'ye kadar varan sıcaklıklarda elektriksel ölçümler alındı. SiC-NWFET, hem düşük hem de yüksek sıcaklıklarda çok yüksek iletkenlik değerleri gösterdi. Ölçülen iletkenlik değerleri sırasıyla oda sıcaklığında ve 350ºC'de 0.43 mS ila 0.3 mS arasındaydı. Ayrıca cihaz, hem oda sıcaklığında hem de yüksek sıcaklıklarda yüksek elektron ve delik mobilitelerinin yanı sıra çok düşük özdirenç değerleri elde etti. Kısacası, iyi verimlilik, düşük güçte çalışma ve ekonomik üretimi bir araya getirdiğimizde, 3C-SiC optoelektronik ve nanoelektronik yüksek sıcaklık uygulamalarının üretimi için çok çekici bir aday haline gelmektedir.
The field of nanomaterials has grown rapidly owing to extensive research on wideband gap semiconductors as an alternative to Si. From a scientific and technological standpoint, their unique electrical and optoelectronic capabilities are of tremendous interest. The rising diversity of application fields necessitates innovative material systems and device designs. These must meet the requirements such as high sensitivity, quick response, and most importantly to withstand harsh environments such as high temperatures. High temperature applications have attracted the most interest from the emerging activity among these harsh environments. Silicon Carbide (SiC), especially 1D and 2D nanostructures has become the material of interest for these high temperature applications due to their outstanding chemical and thermal stability, high breakdown voltage and high drift velocity which gives it the capability to achieve high performance in high temperature environments. This thesis focuses on investigating the impact of high temperatures on SiC thin films and nanowires based UV photodetectors and field-effect transistors. The impact of high temperatures on the performance parameters of SiCTF-UVPD (up to 200°C) and the performance enhancement using Au nanoparticles were investigated successfully. SiCTF-UVPD exhibited a low dark current of 0.08 pA, a fast rise time of 0.34s and a high sensitivity of 4466 at 50°C and bias voltage of 20 V. Moreover, it was observed that Au nanoparticles improved both the sensitivity and the response speed of the photodetector. Finally, single SiCNW based field-effect transistor (SiCNW-FET) was fabricated and characterized from room temperature to 350°C. The SiC-NWFET showed very high transconductance values at both low and high temperatures. The transconductance ranged from 0.43 mS to 0.3 mS at room temperature and 350ºC, respectively. Additionally, the device achieved high electron and hole mobilities as well as very low resistivity values at both room temperature and high temperatures. In short, combining good efficiency, low power operation and economical manufacturing makes 3C-SiC a very attractive candidate for the manufacturing of optoelectronic and nanoelectronic devices for high temperature applications.
The field of nanomaterials has grown rapidly owing to extensive research on wideband gap semiconductors as an alternative to Si. From a scientific and technological standpoint, their unique electrical and optoelectronic capabilities are of tremendous interest. The rising diversity of application fields necessitates innovative material systems and device designs. These must meet the requirements such as high sensitivity, quick response, and most importantly to withstand harsh environments such as high temperatures. High temperature applications have attracted the most interest from the emerging activity among these harsh environments. Silicon Carbide (SiC), especially 1D and 2D nanostructures has become the material of interest for these high temperature applications due to their outstanding chemical and thermal stability, high breakdown voltage and high drift velocity which gives it the capability to achieve high performance in high temperature environments. This thesis focuses on investigating the impact of high temperatures on SiC thin films and nanowires based UV photodetectors and field-effect transistors. The impact of high temperatures on the performance parameters of SiCTF-UVPD (up to 200°C) and the performance enhancement using Au nanoparticles were investigated successfully. SiCTF-UVPD exhibited a low dark current of 0.08 pA, a fast rise time of 0.34s and a high sensitivity of 4466 at 50°C and bias voltage of 20 V. Moreover, it was observed that Au nanoparticles improved both the sensitivity and the response speed of the photodetector. Finally, single SiCNW based field-effect transistor (SiCNW-FET) was fabricated and characterized from room temperature to 350°C. The SiC-NWFET showed very high transconductance values at both low and high temperatures. The transconductance ranged from 0.43 mS to 0.3 mS at room temperature and 350ºC, respectively. Additionally, the device achieved high electron and hole mobilities as well as very low resistivity values at both room temperature and high temperatures. In short, combining good efficiency, low power operation and economical manufacturing makes 3C-SiC a very attractive candidate for the manufacturing of optoelectronic and nanoelectronic devices for high temperature applications.