Fast switching characteristics of (111) oriented cerium oxide thin film-based metal-oxide semiconductor UV photodetector

Abstract

This work presents the studies of cerium oxide (CeO2) thin films (TFs) with different thicknesses on Si substrates using the electron beam evaporation method for photodetector (PD) application in the UV region. The effect of thickness on the structural, morphological, and optoelectronic properties of the TF was comprehensively studied. The structure and crystallinity of the samples were characterized by x-ray diffraction and all TFs showed highly preferred orientation along the (111) plane. The crystallinity and structural parameters like crystallite size, lattice constant, microstrain and dislocation density were also calculated, and 200 nm film showed the best results. Field emission scanning electron microscopy revealed that the CeO2 TF was smoothly deposited on the substrate. The absorption enhanced with increased thickness and thereby, the bandgap energy decreased to 3.45 eV for 300 nm as compared to 3.65 eV for 100 nm thickness. The electrical performance also proved superior for thicker films with increased photocurrent accompanied by lower dark current. The 200 nm CeO2 TF device showed the fastest switching response with a rise time of 240 ms and a fall time of 152 ms at a bias voltage of −4 V with an on/off ratio of 13.59. Moreover, spectral responses were higher for 200 nm film, thus exhibiting good PD performance. It is believed that this work will be highly useful for use as a sensitive UV PD.

Self-Powered Photodetector with High Sensitivity Based on a CeO2/TiO2 Thin Film

“…The current–voltage ( I – V ) curves of the CeO 2 /TiO 2 TF device under dark and light illumination are presented in Figure a, which exhibits the rectifying characteristics under the bias voltage from −6 V to +6. The photocurrent of the device was recorded to be 4.2 × 10 –7 A, which is better than the e-beam-evaporated bare CeO 2 and TiO 2 TF device. , This large photocurrent may be due to an increase in the number of carriers that arises from the effective separation of e – –h + pairs facilitated by the CeO 2 /TiO 2 TF heterojunction. Under light illumination, the e – –h + pairs generated in the CeO 2 /TiO 2 TF heterojunction area rapidly separated due to the built-in electric field between CeO 2 and TiO 2 .…”

“…The separation of these carriers makes recombination less likely near the heterojunction, effectively improving the carrier lifetime . Moreover, the dark current of the CeO 2 /TiO 2 TF device under zero bias voltage was found to be 5.4 × 10 –10 A, which is much lower than those of CeO 2 TF and TiO 2 TF . Furthermore, the CeO 2 /TiO 2 TF device exhibits the photovoltaic effect with an open circuit voltage ( V oc ) of 0.2 V and a short circuit current ( I sc ) of 0.4 × 10 –6 A, as depicted in the enlarged I–V curve [Figure a, inset].…”

Performance analysis of P-SnS thin films fabricated using CBD technique for photo detector applications

“…in thin film solar cells because of their suitable optical and electrical properties. SnS thin films have been prepared using different methods such as vacuum thermal evaporation [6],Co-evaporation [7] ,radio frequency sputtering [8], electron beam evaporation [9], atomic layer deposition [10], Pulse electro deposition [11], Plasma enhanced chemical vapor deposition [12],Spray pyrolysis [13][14][15] chemical bath deposition [16][17], Sol-gel process [18], and electrochemical deposition [19].…”

Effect of SnS thin film thickness on visible light photo detection

“…Recently, the fabrication of photodetectors in visible and NIR regions has fascinated considerable attention due to their broad area of demand in optical imaging, optoelectronic circuits, space communication, industrial quality control, thermal imaging, air quality monitoring, military surveillance, etc [3,4]. Inorganic semiconductor materials like CdS, ZnS, CdSe, InSe [5][6][7][8] and metal-oxide semiconductors such as; CeO 2 , ZnO, and V 2 O 5 have been studied for ultraviolet (UV) photodetector applications [9,10]. Many fields mostly necessitate a photodetector's sensitivity in the visible-light region for applications in various fields.…”