A self-powered ultraviolet photodetector with an extremely high responsivity (54.43 mA W−1) was fabricated by constructing p–n junction of GaN/Ga2O3 films.
Solar-blind
photodetectors have captured intense attention due
to their high significance in ultraviolet astronomy and biological
detection. However, most of the solar-blind photodetectors have not
shown extraordinary advantages in weak light signal detection because
the forewarning of low-dose deep-ultraviolet radiation is so important
for the human immune system. In this study, a high-performance solar-blind
photodetector is constructed based on the n-Ga2O3/p-CuSCN core–shell microwire
heterojunction by a simple immersion method. In comparison with the
single device of the Ga2O3 and CuSCN, the heterojunction
photodetector demonstrates an enhanced photoelectric performance with
an ultralow dark current of 1.03 pA, high photo-to-dark current ratio
of 4.14 × 104, and high rejection ratio (R
254/R
365) of 1.15 × 104 under a bias of 5 V. Excitingly, the heterostructure photodetector
shows high sensitivity to the weak signal (1.5 μW/cm2) of deep ultraviolet and high-resolution detection to the subtle
change of signal intensity (1.0 μW/cm2). Under the
illumination with 254 nm light at 5 V, the photodetector shows a large
responsivity of 13.3 mA/W, superb detectivity of 9.43 × 1011 Jones, and fast response speed with a rise time of 62 ms
and decay time of 35 ms. Additionally, the photodetector can work
without an external power supply and has specific solar-blind spectrum
selectivity as well as excellent stability even through 1 month of
storage. Such prominent photodetection, profited by the novel geometric
construction and the built-in electric field originating from the p–n heterojunction, meets greatly
well the “5S” requirements of the photodetector for
practical application.
Gallium oxide (Ga 2 O 3 ), a typical ultra wide bandgap semiconductor, with a bandgap of ∼ 4.9 eV, critical breakdown field of 8 MV/cm, and Baliga's figure of merit of 3444, is promising to be used in high-power and high-voltage devices. Recently, a keen interest in employing Ga 2 O 3 in power devices has been aroused. Many researches have verified that Ga 2 O 3 is an ideal candidate for fabricating power devices. In this review, we summarized the recent progress of field-effect transistors (FETs) and Schottky barrier diodes (SBDs) based on Ga 2 O 3 , which may provide a guideline for Ga 2 O 3 to be preferably used in power devices fabrication.
The pursuit of high-performance photodetectors functioning
in the solar-blind spectrum is motivated by both scientific and practical
applications ranging from secure communication, monitoring, sensing,
etc. In particular, the fabrication of heterojunctions based on the
wide band gap semiconductors has emerged as an attractive strategy
to promote the high-efficient photogenerated electron/hole pair separation.
However, the precisely controlled growth of heterojunctions remains
a huge challenge. The lattice mismatch leads to the formation of defects
and/or dislocations at the interface, deteriorating the performance
of devices and limiting their envisioned applications. Here, we demonstrate
a simple one-step growth of amorphous/crystalline Ga2O3 phase junctions by using sputtering technique, yielding a
large responsivity of 0.81 A/W, a superior photo-to-dark current ratio
over 107, and an ultrahigh response speed of ∼12
ns. Compared to the previous reported solar-blind photodetectors,
the obtained detectivity ≈ 5.67 × 1014 Jones
is increased by 2 orders of magnitude. Such excellent photoresponse
characteristics can be understood by the interfacial built-in field-promoted
electron/hole pair separation for the amorphous/crystalline Ga2O3 phase junctions. Our results provide a novel
path toward realizing high-performance optoelectronics functioning
in the solar-blind spectrum.
Amorphous gallium oxide thin film with heavy oxygen deficiency was deposited on Pt/Ti/SiO2/Si substrate by pulsed laser deposition in order to explore the resistive switching behavior of the Pt/Ga2O3-x/Pt sandwich structure. A well unipolar resistive switching behavior was obtained in this structure, which exhibits a high resistance ratio of OFF/ON up to 104, non-overlapping switching voltages, and excellent repeatability and retention. Both I-V relation plots of ON and OFF states and temperature dependent variation resistances indicate that the observed resistive switching behavior can be explained by the formation/rupture of conductive filaments formed out of oxygen vacancies.
Flexible photodetectors (PDs) have
become the latest research interest
owing to their potential applications in future implantable sensors
and foldable/wearable optoelectronics. Ga2O3, an emerging ultrawide band gap semiconductor, is considered as
the native photosensitive material for solar-blind PDs. The reported
fabrication temperature of Ga2O3 films is usually
above 600 °C, which hinders its practical application for flexible
devices. In this work, flexible PDs based on graphene/amorphous Ga2O3 van der Waals heterojunctions are fabricated,
which demonstrate promising photoresponse to solar-blind ultraviolet
light. The device yields a high photo-to-dark current ratio (∼105) and large responsivity (22.75 A/W) under 254 nm light illumination,
which could be ascribed to the efficient photogenerated electron–hole
pair separation by the strong built-in field. Moreover, flexible PDs
also show long-term environmental stability and outstanding mechanical
flexibility without any encapsulation. Our work provides a new potential
candidate for realizing cost-effective high-performance flexible optoelectronic
applications.
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