GaN-Based Ultraviolet Passive Pixel Sensor on Silicon (111) Substrate

Abstract

The fabrication of a single pixel sensor, which is a fundamental element device for the fabrication of an array-type pixel sensor, requires an integration technique of a photodetector and transistor on a wafer. In conventional GaN-based ultraviolet (UV) imaging devices, a hybrid-type integration process is typically utilized, which involves a backside substrate etching and a wafer-to-wafer bonding process. In this work, we developed a GaN-based UV passive pixel sensor (PPS) by integrating a GaN metal-semiconductor-metal (MSM) UV photodetector and a Schottky-barrier (SB) metal-oxide-semiconductor field-effect transistor (MOSFET) on an epitaxially grown GaN layer on silicon substrate. An MSM-type UV sensor had a low dark current density of 3.3 × 10−7 A/cm2 and a high UV/visible rejection ratio of 103. The GaN SB-MOSFET showed a normally-off operation and exhibited a maximum drain current of 0.5 mA/mm and a maximum transconductance of 30 μS/mm with a threshold voltage of 4.5 V. The UV PPS showed good UV response and a high dark-to-photo contrast ratio of 103 under irradiation of 365-nm UV. This integration technique will provide one possible way for a monolithic integration of the GaN-based optoelectronic devices.

Selective Annealing Effects of Asymmetric Schottky-Type AlGaN Metal-Semiconductor-Metal UV-B Sensor

“…As shown in Fig. 3(c), the high responsivities under visible region of longer wavelengths beyond 400 nm were attributed to the deep level traps corresponding to the excitation energy above 3.1 eV exist at the AlGaN-Ti/Al/Ni/Au interface (10,11). After the selective annealing, we obtained more reliable responsivity and higher UVRR as shown in Fig.…”

Spectrally Selective Ultrathin Photodetectors Using Strong Interference in Nanocavity Design

“…As previously explained, in equilibrium condition, electrons are trapped in interface defects. When a negative voltage is applied, the trapped electrons can be detrapped and contribute to the overall current [30]. To have a better qualitative comparison, the photoresponsivity of the photodetector is measured from 300 nm to 500 nm under a bias voltage of V = −1V.…”

Mg:TiO2 alloy thin films based MOS capacitors grown on GaAs substrates

“…This fact in turn decreases the leakage current in the Mg containing devices gradually and enhance the η value in a continuous fashion. These trap states may have inhomogeneous distribution [51] at the interface between Au and Mg:TiO2, which shift the minimum ln(I) value towards the reverse bias (fig. 6 (a)).…”