Solar-blind ultraviolet (UV) photodetectors (PDs) have attracted tremendous attention in the environmental, industrial, military, and biological fields. As a representative III-nitride material, ...AlGaN alloys have broad development prospects in the field of solar-blind detection due to their superior properties, such as tunable wide bandgaps for intrinsic UV detection. In recent decades, a variety of AlGaN-based PDs have been developed to achieve high-precision solar-blind UV detection. As integrated optoelectronic technology advances, AlGaN-based focal plane arrays (FPAs) are manufactured and exhibit outstanding solar-blind imaging capability. Considering the rapid development of AlGaN detection techniques, this paper comprehensively reviews the progress on AlGaN-based solar-blind UV PDs and FPAs. First, the basic physical properties of AlGaN are presented. The epitaxy and p-type doping problems of AlGaN alloys are then discussed. Diverse PDs, including photoconductors and Schottky, metal-semiconductor-metal (MSM), p-i-n, and avalanche photodiodes (APDs), are demonstrated, and the physical mechanisms are analyzed to improve device performance. Additionally, this paper summarizes imaging technologies used with AlGaN FPAs in recent years. Benefiting from the development of AlGaN materials and optoelectronic devices, solar-blind UV detection technology is greeted with significant revolutions. Summarizing recent advances in the processing and properties of AlGaN-based solar-blind UV PDs and FPAs as well as AlGaN growth and doping techniques.
Two-dimensional materials are promising candidates for future electronics due to unmatched device performance at atomic limit and low-temperature heterogeneous integration. To adopt these emerging ...materials in computing and optoelectronic systems, back end of line (BEOL) integration with mainstream technologies is needed. Here, we show the integration of large-area MoS
thin-film transistors (TFTs) with nitride micro light-emitting diodes (LEDs) through a BEOL process and demonstrate high-resolution displays. The MoS
transistors exhibit median mobility of 54 cm
V
s
, 210 μA μm
drive current and excellent uniformity. The TFTs can drive micrometre-sized LEDs to 7.1 × 10
cd m
luminance under low voltage. Comprehensive analysis on driving capability, response time, power consumption and modulation scheme indicates that MoS
TFTs are suitable for a range of display applications up to the high resolution and brightness limit. We further demonstrate prototypical 32 × 32 active-matrix displays at 1,270 pixels-per-inch resolution. Moreover, our process is fully monolithic, low-temperature, scalable and compatible with microelectronic processing.
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GEOZS, IJS, IMTLJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZAGLJ
Avalanche and surge robustness involve fundamental carrier dynamics under high electric field and current density. They are also prerequisites of any power device to survive common overvoltage and ...overcurrent stresses in power electronics applications such as electric vehicles, electricity grids, and renewable energy processing. Despite tremendous efforts to develop the next-generation power devices using emerging ultra-wide bandgap semiconductors, the lack of effective bipolar doping has been a daunting obstacle for achieving the necessary robustness in these devices. Here we report avalanche and surge robustness in a heterojunction formed between the ultra-wide bandgap n-type gallium oxide and the wide-bandgap p-type nickel oxide. Under 1500 V reverse bias, impact ionization initiates in gallium oxide, and the staggered band alignment favors efficient hole removal, enabling a high avalanche current over 50 A. Under forward bias, bipolar conductivity modulation enables the junction to survive over 50 A surge current. Moreover, the asymmetric carrier lifetime makes the high-level carrier injection dominant in nickel oxide, enabling a fast reverse recovery within 15 ns. This heterojunction breaks the fundamental trade-off between robustness and switching speed in conventional homojunctions and removes a key hurdle to advance ultra-wide bandgap semiconductor devices for power industrial applications.
Abstract
The sensing properties of monolayer arsenic phosphorus (AsP) for the adsorption of SF
6
, H
2
O, O
2
, and SF
6
decomposition gases (SO
2
and H
2
S) are theoretically investigated by the ...first-principle calculations. We calculate the adsorption energy, equilibrium distance, Mulliken charge transfer, and electron localization function (ELF) to explore whether AsP is suitable for detecting SF
6
decomposition gases. By comparing the adsorption performance of SF
6
, H
2
O, O
2
, and H
2
S gases, we have revealed that the SO
2
gas molecules could form stable chemisorption with AsP monolayer. The results demonstrate that AsP is highly sensitive and selective to SO
2
gas molecules with robust adsorption energy and apparent charge transfer. Furthermore, the current-voltage (
I
–
V
) curves reveal that only the adsorption of SO
2
can largely modify the resistance of AsP. Our results show that gas sensors based on AsP monolayer could be better than that of black phosphorene (BP) to diagnose the state of online gas-insulated switchgear (GIS).
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The electrical and optical properties of Ag/p–GaN contacts have been investigated as a function of the annealing temperature, oxygen concentration, and annealing time. Specific contact resistance (
ρ
...c
) values as low as 1.2 × 10
–4
Ω·cm
2
were obtained from the Ag/p–GaN contact annealed at 400 °C for 60 s in ambient O
2
/N
2
(1:10). We found that the participation of oxygen improves the formation of ohmic contacts. Oxygen might remove the H in Mg–H complexes to activate the Mg acceptors and enhance Ga out-diffusion to form an Ag–Ga solid solution. We also found that the reflectivity of the Ag layer decreases with increasing annealing temperature in the O
2
-containing ambient environment. Thus, an optimal annealing condition of Ag/p–GaN for blue and green LEDs is suggested based on these results. We also used the suggested annealing conditions to form ohmic contacts on DUV LEDs and achieved good electrical performance. The forward voltages of UVC LEDs fabricated with annealed Ag contacts were 6.60 V (7.66 V) at a 40 mA (100 mA) injection current.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Ferroelectric organic field-effect transistors (Fe-OFETs) have attracted intensive attention because of their promising potential in nonvolatile memory devices. The quick switching between binary ...states is a significant fundamental feature in evaluating Fe-OFET memories. Here, we employ 2D molecular crystals via a solution-based process as the conducting channels in transistor devices, in which ferroelectric polymer acts as the gate dielectric. A high carrier mobility of up to 5.6 cm2 V–1 s–1 and a high on/off ratio of 106 are obtained. In addition, the efficient charge injection by virtue of the ultrathin 2D molecular crystals is beneficial in achieving rapid operations in the Fe-OFETs; devices exhibit short switching time of ∼2.9 and ∼3.0 ms from the on- to the off-state and from the off- to the on-state, respectively. Consequently, the presented strategy is capable of speeding up Fe-OFET memory devices by using solution-processed 2D molecular crystals.
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IJS, KILJ, NUK, PNG, UL, UM
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