An Efficient 4H-SiC Photodiode for UV Sensing Applications

Abstract

In this paper, we report experimental findings on a 4H-SiC-based p-i-n photodiode. The fabricated device has a p-type region formed by ion-implantation of aluminum (Al) in a nitrogen doped n-type layer. The dark reverse current density reaches 38.6 nA/cm2 at −10 V, while the photocurrent density rises to 6.36 µA/cm2 at the same bias under λ = 315 nm ultraviolet (UV) radiation with an incident optical power density of 29.83 μW/cm2. At the wavelength of λ = 285 nm, the responsivity is maximum, 0.168 A/W at 0 V, and 0.204 A/W at −30 V, leading to an external quantum efficiency of 72.7 and 88.3%, respectively. Moreover, the long-term stability of the photodiode performances has been examined after exposing the device under test to several cycles of thermal stress, from 150 up to 350 °C and vice versa. The achieved results prove that the examined high-efficiency UV photodiode also has a stable responsivity if subjected to high temperature variations. The proposed device is fully compatible with the conventional production process of 4H-SiC components.

High−Performance 4H−SiC UV p−i−n Photodiode: Numerical Simulations and Experimental Results

“…As shown in Figure 6, the responsivity peak increases with the applied voltage. Moreover, the responsivity increases significantly up to 20 V, while this improvement becomes slower at biases beyond 30 V. In [3], we demonstrated that at the wavelength of λ = 285 nm, the photo−response peak is R = 0.204 A/W at −30V, to our knowledge the best value if compared to those found in the literature, including Schottky photodiodes, p−i−n, and more sophisticated bipolar devices. Moreover, the calculated External Quantum Efficiency (EQE), defined as the photodiode's capability to convert an optical flux into an electrical energy, is 72.7%, the maximum value ever reported for UV photodiodes with no bias applied.…”

“…Here, we extend the previous experimental results [3] up to 60 V, in reverse bias, and the corresponding spectral responsivities of the 4H−SiC p−i−n photodiode, for both experiments and simulations, are compared to each other, from 0 V to 60 V in steps of 10 V, at the same wavelengths of interest.…”

“…In our setup, UV radiation generated by a remotely controlled monochromator was used to illuminate the devices under test during the measurement of the J−V characteristics at different wavelengths in the range between λ = 190 nm and 400 nm, in steps of 5 nm. More details about the experimental results, up to 30 V DC in reverse bias applied between top (anode) and bottom (cathode) p−i−n diode contacts, and the used electro−optical setup, are reported in [3]; a schematic picture is however shown in Figure 5 together with the fabricated microchip, containing several photodiodes, bonded on a custom Printed Circuit Board (PCB), which allows a stable connection between devices and the measurement instrumentations. In [3], we demonstrated that at the wavelength of λ = 285 nm, the photo−response peak is R = 0.204 A/W at −30V, to our knowledge the best value if compared to those found in the literature, including Schottky photodiodes, p−i−n, and more sophisticated bipolar devices.…”

“…More details about the experimental results, up to 30 V DC in reverse bias applied between top (anode) and bottom (cathode) p−i−n diode contacts, and the used electro−optical setup, are reported in [3]; a schematic picture is however shown in Figure 5 together with the fabricated microchip, containing several photodiodes, bonded on a custom Printed Circuit Board (PCB), which allows a stable connection between devices and the measurement instrumentations. In [3], we demonstrated that at the wavelength of λ = 285 nm, the photo−response peak is R = 0.204 A/W at −30V, to our knowledge the best value if compared to those found in the literature, including Schottky photodiodes, p−i−n, and more sophisticated bipolar devices. Moreover, the calculated External Quantum Efficiency (EQE), defined as the photodiode's capability to convert an optical flux into an electrical energy, is 72.7%, the maximum value ever reported for UV photodiodes with no bias applied.…”

“…During the past decade, high−performing 4H−SiC [3] and 6H−SiC [4,5] UV photodetectors have been more widely studied. Different structures have been proposed, such as p−i−n [6,7], Schottky [8], avalanche [9,10], and metal-semiconductor-metal (MSM) UV photodetectors [11].…”