Photophysical investigation of the formation of defect levels in P doped ZnO thin films

Mondal, Sourav; Basak, Durga

doi:10.1016/j.ceramint.2022.03.275

Cited by 13 publications

(8 citation statements)

References 74 publications

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“…The peak at 3.14 eV in both the samples corresponds to transition from CBM to shallow acceptor level P Zn -2V Zn . As it is reported that this level lie between 0.20 and 0.18 eV above VBM [44]. The peak appeared at 3.14 eV is logically at 0.19 and 0.18 eV above VBM for sample PZ74 and PZ84 simultaneously.…”

Section: Optical Propertiesmentioning

confidence: 57%

Unfolding the conductivity reversal n- to p-type in phosphorus-doped ZnO thin films by spin-on dopant (SOD) process

Mishra¹,

Saha²,

Bhowmick³

et al. 2022

J. Phys. D: Appl. Phys.

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Phosphorus doping induced p-type doping in ZnO thin films based on spin-on dopant (SOD) process is reported in this article. Owing to the reduced dependence on the conventional amenities for diffusion/ion-implantation doping, the SOD process provides a simple and cheap doping method. The effect of SOD process temperature on conductivity ZnO thin films is investigated by altering the temperature from 700 oC to 1000 oC. Systematic FESEM analysis demonstrates the impact of doping temperature on the morphological properties of SOD. The X-ray diffraction (XRD) measurements reveal that the p-type ZnO thin films had (002) preferred crystal orientation. At the same time, X-ray photoelectron spectroscopy (XPS) validated the formation of the PZn–2VZn complex, which was responsible for the acceptor behaviour of films. Moreover, the photoluminescence spectra tracked down that the origin of 3.35 and 3.32 eV emission peaks is due to the acceptor bound exciton and free-electron to acceptor level transitions, respectively. Finally, an elevated hole concentration of 2.09×1016 cm-3 is achieved with a resistivity of 1.14 Ω-cm at 800 oC doping temperature. However, the film doped at 900oC and 1000oC showed n-type behaviour due to the generation of high concentration donor defects. Here, we successfully demonstrate that the SOD process has great potential to produce high-quality p-type ZnO thin films suitable for optoelectronic devices applications.

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Section: Optical Propertiesmentioning

confidence: 57%

Unfolding the conductivity reversal n- to p-type in phosphorus-doped ZnO thin films by spin-on dopant (SOD) process

Mishra¹,

Saha²,

Bhowmick³

et al. 2022

J. Phys. D: Appl. Phys.

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“…ZnO NRs/ZnO film shows photoresponse with a photosensitivity value of 1.12 under 350 nm UV illumination due to band edge absorption and photocarrier generation. A small response with a photosensitivity of 1.04 is also observed under 500 nm illumination, which is associated with the in-gap defect levels in ZnO . Also, the photoresponse is very slow for the ZnO NRs/ZnO film.…”

Section: Resultsmentioning

confidence: 93%

“…A small response with a photosensitivity of 1.04 is also observed under 500 nm illumination, which is associated with the in-gap defect levels in ZnO. 48 Also, the photoresponse is very slow for the ZnO NRs/ZnO film. Under NIR illumination, no photoresponse has been observed.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Ultrafast and Ultrabroadband UV–vis-NIR Photosensitivity under Reverse and Self-Bias Conditions by n⁺-ZnO/n-Si Isotype Heterojunction with >1 kHz Bandwidth

Mondal

Halder

Basak

2023

ACS Appl. Electron. Mater.

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A high-performance broadband photodetector has attracted significant attention due to its wide range of applications. We report an n+-ZnO/n-Si isotype heterojunction by depositing ZnO nanorods followed by a ZnO thin film on an n-type undoped Si wafer for detecting a broad wavelength from 300 to 940 nm with a high speed under reverse as well as zero bias conditions. Under 1.5 V reverse and zero bias, the device provides responsivity values up to ∼200 and ∼13 mA/W respectively. Under self-bias, the n+-ZnO/n-Si heterojunction exhibits up to 1.2 × 103 photosensitivity. The n+-ZnO/n-Si heterojunction can detect power as low as 10–12 μW/cm2. A photoresponse up to 2 kHz modulated illuminations has been measured, and the ultrafast n+-ZnO/n-Si heterojunction provides a stable and rapid photoresponse with a response time in the 60–120 μs range. The n+-ZnO/n-Si heterojunction exhibits a −3 dB cutoff frequency of >2000 and 1100 Hz under reverse and zero bias, respectively. Therefore, we unprecedentedly demonstrate an n+-ZnO/n-Si isotype heterojunction as a potential candidate for detecting light in a broad ultraviolet to infrared region with a very high speed and >1 kHz frequency bandwidth as well.

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“…The deconvoluted peak values are given in table 5 for all samples. For sample 3 the band edge (BE) peak is observed at 3.24 eV which corresponds to UVPL transition in the bandgap [12]. For samples 1 and 2 the donor-like defect-related transitions are more as compared to sample 3.…”

Section: Optical Analysismentioning

confidence: 97%

Temperature induced conductivity reversal in ZnO thin films

Mishra

Bhowmick

Saha

et al. 2023

Oxide-Based Materials and Devices XIV

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ZnO is a fascinating large gap (3.37 eV) semiconductor, which exhibits intrinsically n-type conductive due to its native defects such as zinc interstitials and oxygen vacancies and such n-type related defects tend to compensate the p-type acceptor defects. However, the generation process of p-type defects is more challenging for developing a good quality homojunction optical device. Here we have studied the effect of ex-situ atmospheric annealing on conductivity of ZnO films. The ZnO films were deposited using RF sputtering on Si substrate temperature at 400°C substrate temperature and 2.2E-2 mbar gas pressure. The films were deposited in oxygen-rich ambient to achieve less oxygen vacancy defects in the film. The ex-situ atmospheric annealing is performed at higher temperature of 900 and 1000ºC. The effects of this postdeposition annealing on the electrical, structural, elemental and optical properties of ZnO thin films were investigated in detail. The X-ray Diffraction (XRD) results exhibited the hexagonal wurtzite structure (002) orientation. After annealing, the XRD peak is shifted at higher 2-thetha value, which indicates a reduction in lattice constant. Further, X-ray photoelectron spectroscopy (XPS) had been done and such XPS results confirmed that simultaneous generation of acceptor defects and reduction of oxygen vacancy related donor concentrations. The electrical properties of films were studied using hall measurement system. These electrical parameters were purposive to inspect the effect of ex-situ atmospheric annealing temperatures on conductivity of films. The Hall measurement confirmed that 1000ºC annealed films achieve p-type conductivity with high reproducibility and such p-type behavior exhibits high mobility. Thus, temperature induced conductivity reversal could be a potential and cost-effective technique to achieve highly stable p-type ZnO films.

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Photophysical investigation of the formation of defect levels in P doped ZnO thin films

Cited by 13 publications

References 74 publications

Unfolding the conductivity reversal n- to p-type in phosphorus-doped ZnO thin films by spin-on dopant (SOD) process

Unfolding the conductivity reversal n- to p-type in phosphorus-doped ZnO thin films by spin-on dopant (SOD) process

Ultrafast and Ultrabroadband UV–vis-NIR Photosensitivity under Reverse and Self-Bias Conditions by n⁺-ZnO/n-Si Isotype Heterojunction with >1 kHz Bandwidth

Temperature induced conductivity reversal in ZnO thin films

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Photophysical investigation of the formation of defect levels in P doped ZnO thin films

Cited by 13 publications

References 74 publications

Unfolding the conductivity reversal n- to p-type in phosphorus-doped ZnO thin films by spin-on dopant (SOD) process

Unfolding the conductivity reversal n- to p-type in phosphorus-doped ZnO thin films by spin-on dopant (SOD) process

Ultrafast and Ultrabroadband UV–vis-NIR Photosensitivity under Reverse and Self-Bias Conditions by n+-ZnO/n-Si Isotype Heterojunction with >1 kHz Bandwidth

Temperature induced conductivity reversal in ZnO thin films

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Ultrafast and Ultrabroadband UV–vis-NIR Photosensitivity under Reverse and Self-Bias Conditions by n⁺-ZnO/n-Si Isotype Heterojunction with >1 kHz Bandwidth