Three-Dimensional Design of a 4H-SiC NPN Lateral Phototransistor for Micro-Pixel in Ultraviolet Optoelectronic Integration

Micro-pixels based on 3-D 4H-silicon carbide (4H-SiC) NPN phototransistors for optoelectronic integration are designed and analyzed in this article for the first time. Pixels with linear, hexagonal, and octagonal layouts demonstrate different results in optical responsivity, delay, spectral response, and high-temperature characteristic. The device operates at a low biased voltage of 5 V. Under 270-nm ultraviolet (UV) illumination, the responsivity of the hexagonal structure reaches 254 A/W at 300 K, and the spectral response shows a great potential of deep UV detection of wide-range wavelength. Furthermore, the transient delay is reduced by large junction area ratio due to the new structure design. The lowest delay performed by the octagonal structure is
$55~\mu \text{s}$
, which reveal the potential of high-frequency application. Under high-temperature conditions, the responsivity of the device is significantly improved. The responsivity of hexagonal type can reach 1050 A/W at a light intensity of
$100~\mu \text{W}$
/cm2, which is suitable for detecting weak UV light in elevated temperature environments up to 800 K. Overall, micro-pixel with octagonal structure holds great potential for applications in high-resolution UV imaging in high-temperature environments.