Investigation the Performance of Cr-Doped ZnO Nanocrystalline Thin Film in Photodiode Applications

Undoped and Cr-doped zinc oxide (ZnO) thin films were deposited on the glass and p-Si substrates by the chemical spray pyrolysis technique. The films were characterized by x-ray diffractometry (XRD) and UV-visible spectrometry, and electrical characterization was achieved by using the films as an interfacial layer between the Au and p-Si. The XRD results confirmed the undoped and Cr-doped ZnO thin film crystalline structures. UV-visible spectra provided the transmittance plots and band gap energy values. I-V measurements were performed on the fabricated Au/ZnO/p-Si and Au/ZnO:Cr/p-Si devices to determine the effect of the ZnO interfacial layer on their performance. Various junction parameters, such as the ideality factor, barrier height, and series resistance, were calculated from the I-V measurements by various techniques, and have been discussed in detail. A 100-mW/cm(2) power intensity light was exposed on the Au/ZnO:Cr/p-Si device to see the photodiode behavior as well as to determine light sensitivity parameters such as photosensitivity and detectivity. The results highlight that the Au/ZnO:Cr/p-Si device can be thought of for optoelectronic application

Structural, optical and electrical characterization of Mn3O4 thin films via Au composite

Metal oxides have been gained great interest and investigated by scientist for many years because they can be employed easily and cost effectively for technological applications such as sensors, diodes and solar cells. The metal oxides should be studied to increase their efficiency for technological applications. For that aim, the bare Mn3O4 and Mn3O4/Au composite thin films were synthesized by spray pyrolysis technique and, they were characterized via x-ray diffractometer (XRD), Raman spectroscopy, UV-vis spectroscopy, SEM, energy dispersive x-ray spectroscopy (EDS) and four point probe technique. XRD results show that the Mn3O4 thin film has amorphous structure but, the Mn3O4/Au composite thin film has crystalline structure in nature. Raman spectroscopy results highlight that the Mn3O4/Au thin film exhibit Mn-O bonding with Au peaks and better crystalline structure while the Mn3O4 thin film has only Mn-O bonding. According to UV-vis spectrometer results, both band gap energy and transmittance values of the Mn3O4 thin film decreased by adding Au to the structure. SEM images reveal that adding Au to the Mn3O4 structure heal its morphological properties. The EDS results confirm that bare the Mn3O4 and Mn3O4/Au composite thin films were obtained successfully. The Mn3O4/Au composite thin film has lower sheet resistance than bare ones. The Mn3O4/Au thin film can be used for supercapacitor and sensor applications. © 2018 IOP Publishing Ltd

Characterization of Al/In:ZnO/p-Si photodiodes for various In doped level to ZnO interfacial layers

The detection of the light by a device is so important for industrial applications such as energy harvesting, sensing and switching. For that aim, we have introduced various In doped (0%, 0.1%, 0.5% and 1.0%) nanostructure ZnO thin films which was prepared by the sol-gel spin coating technique as interfacial materials between the Al metal and p-type Si for investigation photodetection properties of the material. According to morphological results of the In doped ZnO thin films at AFM, undoped and In doped ZnO thin films formed as fiber like structures. The obtained optical band gap energy for undoped, 0.1%, 0.5% and 1.0% In doped ZnO thin films were determined as 3.293 eV, 3.283 eV, 3.272 eV and 3.263 eV, respectively. The Al/In:ZnO/p-Si devices were characterized with I–V and C–V measurements. The I–V data was acquired under various illumination conditions to see the response of the devices to the light. The I–V characteristics have revealed that the devices have high ideality factors and, their values usually increased with increasing In doping level, but the rectifying properties decreased. In addition, barrier heights and series resistance values decreased with increasing In doping level. Also, the device parameters were calculated via Cheung and Norde methods for accuracy of the results. The current transient measurements highlighted that In doping provided to increase of light response. The C–V measurements have imparted that the capacitance values are strong function of the frequency and voltage for various In doping level. The devices can be thought and improved as photodiode and photodetector applications in the industry. © 2018 Elsevier B.V

Al/Si3N4/p-Si aygıtının C-V characteristikleri üzerine metal ile yarıiletken kontak arasındaki yalıtkan tabakanın kalınlık etkisi

Metal-Yalıtkan-Yarıiletken (MIS) yapılar elektronik ve optoelektronikteki iyi uygulamalarından büyük ilgiye sahiptirler. Bu yapıların önemi tabaka depolama özelliği, kapasitans etkisi ve yüksek dileketrik sabitlerine sahip olmalarına dayandırılabilir. Bu yüzden Si3N4 tabakalı iki adet numune plazma destekli kimyasal buhar biriktirme (PECVD) yöntemiyle birinin kalınlığı 5 nm diğerinin kalınlığı 50 nm olacak şekilde p-tip Si üzerine büyütüldü. Si3N4 tabakasının kalınlığı bir elipsometreyle kontrol edildi. Al/Si3N4/p tip Si kontağın üzerine Si3N4 tabakasının kalınlık etkisi 10 kHz-1 MHz frekans değerleri için -5 V’tan +5 V voltaj aralığında yapıların kapasitans-voltaj (C–V) ve iletkenlik-voltaj (G–V) karakteristikleri ile oda sıcaklığında araştırıldı. Farklı kalınlığa sahip kontakların her bir durumda kapasitans değerlerinin artan frekansla azaldığı ve iletkenlik değerlerinin arttığı tespit edildi. Ara yüzey durumları (Nss) ve Seri direnç (Rs) etkileri, bariyer yüksekliği (Φb) ve taşıyıcı yoğunluğu (Na) kapasitans-voltaj (C–V) ve iletkenlik-voltaj (G–V) karakteristikleri karakterizasyonlardan elde edildi ve açıklandı. Ayrıca 5 nm ve 50 nm kalınlık değerindeki tabakalar için 500 kHz frekansta çift yönlü C-V ve G-V karakterizasyonlarından elde edildi ve kıyaslandı. Sonuç olarak, Si3N4 tabakasının kalınlık değişiminin kontakların özelliklerini etkilediği görüldü ve bu kontakların Memrezistör yapısına sahiptirler ve gelecekte hafıza aygıtları için kullanılabilir ve geliştirilebilirler

Structural, optical and magnetic properties of Ni-Co co-doped ZnO thin films

Undoped and Ni-Co co-doped ZnO thin films were successfully prepared by using spray pyrolysis technique. XRD analysis reveals that the secondary phases are not to be formed and confirms that Ni2+ and Co2+ ions are successfully penetrated into ZnO lattice. Raman spectra of undoped and Ni-Co co-doped ZnO thin films show that the films have Raman-active modes of crystalline wurtzite structure and defect vibration depending on Ni-Co co-doping. Furthermore, an additional peak (around 560 cm-1) appears with Ni-Co co-doping in Raman analysis, indicating the existence of oxygen vacancy defects. Ultraviolet-visible measurements show a red shift of ZnO band gap with Ni-Co co-doping. The red shift can be attributed to the sp-d exchange interaction between the localized d-electrons of Ni2+ and Co2+ ions and the band electrons in ZnO lattice. The surface morphologies of both thin films were examined by SEM. It is observed that both thin films have homogenous surface. Magnetization curve reveals that Ni-Co co-doped thin film has room temperature ferromagnetic (RTFM) behavior. The RTFM ordering has been elucidated with respect to intrinsic defects in the frame of bound magnetic polaron model. Ni-Co co-doped thin film can be employed as DMS material in spintronic applications. © 2019 IOP Publishing Ltd

Influences of Pr and Ta doping concentration on the characteristic features of FTO thin film deposited by spray pyrolysis

The Pr and Ta separately doped FTO (10 at.% F incorporated SnO2) films are fabricated via spray pyrolysis. The microstructural, topographic, optical, and electrical features of fluorine-doped TO (FTO) films are investigated as functions of Pr and Ta dopant concentrations. The x-ray diffraction (XRD) measurements reveal that all deposited films show polycrystalline tin oxide crystal property. FTO film has (200) preferential orientation, but this orientation changes to (211) direction with Pr and Ta doping ratio increasing. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) analyses show that all films have uniform and homogenous nanoparticle distributions. Furthermore, morphologies of the films depend on the ratio between Pr and Ta dopants. From ultraviolet-visible (UV-Vis) spectrophotometer measurements, it is shown that the transmittance value of FTO film decreases with Pr and Ta doping elements increasing. The band gap value of FTO film increases only at 1 at.% Ta doping level, it drops off with Pr and Ta doping ratio increasing at other doped FTO films. The electrical measurements indicate that the sheet resistance value of FTO film initially decreases with Pr and Ta doping ratio decreasing and then it increases with Pr and Ta doping ratio increasing. The highest value of figure of merit is obtained for 1 at.% Ta- and Pr-doped FTO film. These results suggest that Pr- and Ta-doped FTO films may be appealing candidates for TCO applications

Temperature dependent current-voltage characteristics of Al/TiO2/n-Si and Al/Cu:TiO2/n-Si devices

We fabricated undoped and Cu doped TiO2 thin films by spin coating technique and employed the films as interfacial oxide layer between the Al and n-type Si to investigate the effect of temperature on the Al/TiO2/n-Si and Al/Cu:TiO2/n-Si devices. For that aim, the I–V measurements were performed in the range of 50 K–400 K by 50 K interval. The devices exhibited good rectifying behavior and thermal response in a wide range temperature. Ideality factor, barrier height and series resistance were calculated from I–V measurements for various temperatures by thermionic emission theory, Norde and Cheung methods and discussed in the details. The obtained results revealed that the device parameters are a strong function of the temperature. The interface states (Nss) were affected by the changing of the temperatures. The Al/TiO2/n-Si and Al/Cu:TiO2/n-Si devices can be performed for wide range temperatures in various technological applications. © 2019 Elsevier Ltd16401044This work is supported by Selçuk University BAP of?ce with Project Numbers 16401044 . Authors would like to acknowledge the support of the Selçuk University for this research

Perovskite/p-Si photodiode with ultra-thin metal cathode

Perovskites have attracted great interest because they provide promising improvement for solar cells. Yet, the perovskites have not been extensively used by the researchers for diode applications. In this study, both Al/p-type Si and Al/perovskite/p-type Si devices have been obtained. We used a facile and cost-effective way of making perovskite thin film layer between the ultra-thin metal and semiconductor as an interfacial layer by spin coating technique as well distributed film. In order to keep costs low, aluminum was chosen as the cathode material. The Al/p-type Si and Al/perovskite/p-type Si devices have exhibited good rectifying properties and calculated rectifying ratio of the devices are 2.39 × 103 and 4.56 × 104 at 1 V, respectively. Photodiode properties of the device have been illustrated and discussed in the details by calculating some diode parameters. While the Al/p-type Si device has 1.53 ideality factor value and 0.72 eV barrier height, the ideality factor and barrier height values of Al/perovskite/p-type Si device have been obtained as 2.12 and 0.87 eV, respectively under dark condition. The solar cell efficiency and fill factor values of the Al/perovskite/p-type Si device are 7.44 × 10-3 and 23.7, respectively. Such devices can find applications as rectifiers and photodiodes in industry. © 2018 Elsevier Lt

A comparison of the electrical characteristics of TiO2/p-Si/Ag, GNR-TiO2/p-Si/Ag and MWCNT-TiO2/p-Si/Ag photodiodes

The TiO2/p-Si/Ag, graphene nanoparticles doped (GNR) TiO2/p-Si/Ag and multi-walled carbon nanotube (MWCNT) doped TiO2/p-Si/Ag photodiodes were fabricated by electro-spinning technique at the same experimental conditions, and their structural, morphological and electrical properties were compared for photodiode applications. XRD measurements were confirmed undoped, GNR and MWCNT doped TiO2 structures, and brookite phase of (121) preferred orientation TiO2 has been observed from XRD patterns. SEM images of the heterojunctions showed that undoped and doped TiO2 layer have homogenous surfaces. I–V measurements were performed for electrical characterization of the TiO2/p-Si/Ag, GNR-TiO2/p-Si/Ag and MWCNT-TiO2/p-Si/Ag photodiodes under dark and light illumination conditions at room temperatures. The results imparted that all heterojunctions have good rectifying and photodiode properties. Some heterojunction parameters such as ideality factor, barrier height, series resistance were calculated and discussed in details according to thermionic emission theory, Cheung and Norde techniques. The determined ideality factor values are 8.55, 9.70 and 8.99, and barrier height values are 0.75 eV, 0.74 eV and 0.73 eV for the TiO2/p-Si/Ag, GNR-TiO2/p-Si/Ag and MWCNT-TiO2/p-Si/Ag photodiodes, respectively. These heterojunctions can be considered and improved as photodiodes in industrial applications. © 2019, Springer Science+Business Media, LLC, part of Springer Nature

The effect of indium doping concentration on the electrical and dielectric properties of Al/In:ZnO/p-Si heterojunctions

Undoped and 0.1% 0.5% and 1.0% indium doped ZnO thin films were obtained by spin coating method as interfacial thin film layer between Al metal and p-Si semiconductor to investigate dielectric properties of the Al/In:ZnO/p-Si heterojunctions. Impedance spectroscopy technique was employed to characterize the dielectric properties of the Al/In:ZnO/p-Si heterojunctions depending on frequency (from 10 kHz to 1 MHz) and voltage (from -5 V to +5 V). The results imparted that interface states (Nss), series resistance (Rs), barrier height (?b) and the concentration of acceptor atoms (Na) influenced frequency changes. The dielectric parameters such as dielectric constant (?'), dielectric loss (?¨), loss tangent (tan ?), real and imaginary parts of the electric modulus (M' and M¨) and ac electrical conductivity (?) values were calculated from impedance spectroscopy measurements and discussed in details for changing frequency and voltage for various In doped ZnO thin film interlayers. The dielectric properties of the Al/In:ZnO/p-Si heterojunctions were affected both In doping concentration and the frequency and voltage changes. The Al/In:ZnO/p-Si heterojunctions can be considered for industrial applications to increase the control. © 2019 Elsevier B.V