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Surface modification of AlN using organic molecular layer for improved deep UV photodetector performance
摘要： Direct wide bandgap of 6.2 eV, high temperature robustness and radiation hardness make aluminum nitride (AlN) a preferable semiconductor for deep ultraviolet (UV) photodetection. However, the performance and reliability of AlN- based devices is adversely affected by a large density of surface states present in AlN. In this work, we have investigated the potential of a monolayer of organic molecules in passivating the surface states of AlN which improved the performance of AlN- based metal- semiconductor- metal (MSM) deep UV photodetectors. The organic molecules of Meso-5,10,15-triphenyl-20-(p-hydroxyphenyl)porphyrin Zn(II) complex (ZnTPP(OH)) were successfully adsorbed on AlN surface, forming a self- assembled monolayer (SAM). The molecular layer was characterized by contact angle measurement, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The surface modification of AlN effectively reduced dark current of the photodetector by ten times without degrading the magnitude of photo current, especially at low voltages. Photo to dark current ratio (PDCR) was enhanced from 930 to 7835 at -2V and the responsivity doubled from 0.3 mA/W to 0.6 mA/W at 5V. Moreover, the rise and fall times of the detector were found to decrease after the surface modification process. Our results suggest that SAM of porphyrin molecules effectively passivated the surface states in AlN which resulted in improved photodetector performance.
关键词： Dark current,PDCR,MSM UV photodetector,Surface states,SAM,Responsivity,Temporal response
更新于2025-09-23 15:19:57
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[IEEE 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Bengaluru, India (2018.12.17-2018.12.19)] 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Improvement in Self-Powered GaN-based Symmetric Metal-Semiconductor-Metal Ultraviolet Photodetectors by Using Phenol-Functionalized Porphyrin Organic Molecules
摘要： Organic molecular monolayers have been used for improving the performance of various electronic device structures. In this work, the concept of organic molecular surface modification is applied for improving the performance and the self-power quality of GaN-based symmetric Metal-Semiconductor-Metal (MSM) Ultraviolet (UV) Photodetectors (PDs). Organic molecules of phenol-functionalized-metallated-Porphyrin (Zn-TPPOH) have been adsorbed on GaN epitaxial layers and Ni/Zn-TPPOH/GaN/Zn-TPPOH/Ni PD structures have been fabricated. This process has led to decrease in reverse bias dark current by ~ 10,000 times at 0V in comparison to the dark current values obtained for Ni/GaN/Ni MSM PDs. Photodetector parameters such as Photo-to-dark current ratio and Responsivity have increased from 8.8 and 0.004 A/W for Ni/GaN/Ni structures to 2.4×105 and 0.038 A/W for Ni/Zn-TPPOH/GaN/Zn-TPPOH/Ni structures, respectively at 0V. The spectral selectivity of the PDs has also improved at 0V, which means that the molecularly modified devices have become more responsive in UV spectral region and lesser in visible spectral region, if compared to bare-GaN based devices.
关键词： PDCR,Responsivity,Spectral selectivity
更新于2025-09-16 10:30:52