Ultrahigh Responsivity β-Ga2O3/BP Junction Field Effect Phototransistors for UV/IR Dual-Band Detection

In this work, a dual-band junction field effect phototransistor (JFEPT) was fabricated by integrating p-type black phosphorus (BP) with Si-doped
$\beta $
-Ga
₂
O
₃
. The operation principle of the JFEPT was systematically investigated by commercial TACD software SILVACO. The results indicate that the photocurrent is mainly formed by electrons under short-wave radiation, while it is composed of electrons and holes under long-wave irradiation. In addition, the Ga
₂
O
₃
doping concentration was determined to be
$3\times 10^{{16}}$
cm
$^{-{3}}$
to obtain a large photo-to-dark current ratio (PDCR). The threshold voltage (
${V}_{\text {th}}{)}$
of the fabrication JFEPT was 0.65 V, indicating that the device working in normally- OFF state. The drain current was
$\sim 10^{-{6}}$
mA/mm and the ON/ OFF ratio is
$10^{{5}}$
at
${V}_{G}$
= −4 V and
${V}_{\text {DS}}$
= 5 V. And the device exhibits a low leakage current of
$2.84\times 10^{-{6}}$
mA/mm. Under 254- and 808-nm illumination, the PDCR were 14713.79 and 5.53, and the responsivity was calculated to be
$2.39\times 10^{{6}}$
and 535 mA/W, respectively. In addition, a low noise current of 0.17 nA/Hz
$^{\text {1/{2}}}$
at 1 Hz is beneficial for the device to detect the ultraweak optical signal. This work provides an important reference for the realization of high-performance UV-IR dual-band detector.