High‐Performance Harsh‐Environment‐Resistant GaO_X Solar‐Blind Photodetectors via Defect and Doping Engineering

Abstract

photodetector (SBPD), as an indispensable part of spectral detectors, plays important roles distinctively in various crucial applications, such as missile tracking, flame prewarning, secure communication, and environment monitoring. [1][2][3][4] In terms of the possible harsh application environment, high-performance SBPDs with excellent tolerance towards high temperature, high voltage, and high radiation, are required inevitably. Based on low cost and mature technology, the currently available Si-based SBPDs are facing the challenges of filter dependence, low penetration depth of high-energy ultraviolet (UV) photons, and finite responsivity (R) towards solar-blind region. [5][6][7] Especially, Si-based SBPDs suffer serious thermal instability owing to the narrow bandgap, which suppresses their high-temperature applications. Advanced SBPDs based on wide bandgap (WBG) materials, such as MgZnO, [8] AlGaN, [9,10] diamond, [11] and Ga 2 O 3 , [12] are believed as subversive substitutes of Si-based SBPDs. Among the various WBG materials, Ga 2 O 3 is the most desirable candidate for SBPDs applications based on the facts that, i) its ultra-wide bandgap (4.5-4.9 eV) corresponds to the solar-blind region directly without the necessity of bandgap modulation by doping or alloying process; [13] ii) its high absorption coefficient for high-energy UV photons benefits outstanding sensitivity in solar-blind region; [14] iii) it balances high solar-bind response and material workability; [15] iv) its large-size bulk single crystals can be put into mass production by low-cost melt-grown methods; [16] and most importantly, v) it has high structural stability toward temperature, radiation, and electric field for harsh-environment application. [17] High-quality Ga 2 O 3 material, including single-crystal substrates, nanostructures, and epitaxial films, [14,18,19] facilitate sharp junction interface, such as P-N heterojunction, [20] N-N heterojunction, [21] phase junction, [22] and Schottky junction, [23] to improve the solar-blind response performance. Nevertheless, so far, high-performance SBPDs based on high-quality Ga 2 O 3 Gallium oxide (Ga 2 O 3 ), with an ultrawide bandgap, is currently regarded as one of the most promising materials for solar-blind photodetectors (SBPDs), which are greatly demanded in harsh environment, such as space exploration and flame prewarning. However, realization of high-performance SBPDs with high tolerance toward harsh environments based on low-cost Ga 2 O 3 material faces great challenges. Here, defect and doping (DD) engineering towards amorphous GaO X (a-GaO X ) has been proposed to obtain ultrasensitive SBPDs for harsh condition application. Serious oxygen deficiency and doping compensation of the engineered a-GaO X film ensure the high response currents and low dark currents, respectively. Annealing item in nitrogen of DD engineering also incurs the recrystallization of material, formation of nanopores by oxygen escape, and suppression of sub-bandgap defect states. As a result, the tailored GaO...

Aqueous‐Printed Ga2O3 Films for High‐Performance Flexible and Heat‐Resistant Deep Ultraviolet Photodetector and Array

“…Although no peaks appeared in the Raman and XRD spectra of the S350 film, FTIR spectra in Figure S1d (Supporting Information) further ruled out the presence of GaOOH, identifying that the S350 film had totally converted to amorphous Ga 2 O 3 assisted by its XRD spectra results in Figure 2b. [38,39] In spite of the similar element ratios of S350 and S900 (Figure S2, Supporting Information), the following phenomena further support the crystallization process of Ga 2 O 3 in the S900 film during 900 °C annealing, including i) reduction of oxygen vacancies reflected by the decreased ratio of O II /(O I +O II ) (Figure 2c), [24,40] ii) enhancement of intrinsic ultraviolet emission caused by the recombination of free electrons and self-trapped holes, iii) suppression of visible-light (blue and green) emission attributed to the excitation of vacancy and interstitial defects of both oxygen and gallium (Figure 2d), [41,42] and iv) inhibition of carrier lifetime possibly due to the diminished defect-induced traps (Figure 2e). [43,44] These results solidly demonstrate that the printed Ga 2 O 3 film obtains higher crystallinity and the intrinsic defects are significantly reduced during the annealing process.…”

“…Compared with the control devices (S org 900 in Figure S3, Supporting Information and S350 in Figure S4, Supporting Information), the suppressed I dark of the S900 device can be attributed to the enlarged resistance of the Ga 2 O 3 films caused by recrystallization and the possible N-doping compensation during 900 °C annealing. [24] The I photo multiplication of the S900 device is possibly due to the large internal gain caused by abundant self-trapped holes in the annealing-optimized films.…”

“…[19][20][21][22] In addition, Ga 2 O 3 exhibits high robustness toward chemical corrosion, temperature, radiation, and electric fields, making it competent for harsh environment applications. [23][24][25] To date, the exploration of flexible Ga 2 O 3 DUV photodetectors is still in its infancy. Flexible Ga 2 O 3 DUV photodetectors have been studied based on traditional sputter or atomic layer deposition technologies and have achieved decent performance.…”

Thermally Stable Organic Field‐Effect Transistors Based on Asymmetric BTBT Derivatives for High Performance Solar‐Blind Photodetectors

“…[ 3 , 4 , 5 ] Compared to photodiodes, phototransistors based on organic, inorganic, and organic–inorganic hybrid semiconductor materials demonstrate unique advantages of low noise, high sensitivity, and signal‐amplification function, [ 6 , 7 , 8 , 9 , 10 , 11 , 12 ] which have been drawing great research interest in solar‐blind photodetectors. [ 13 , 14 , 15 , 16 , 17 ] Among them, organic semiconductors, which possess low cost, mechanical flexibility, controllable molecular structure, and tunable optoelectronic properties, [ 18 , 19 , 20 , 21 , 22 , 23 ] would render potential applications in flexible and wearable photo response electronic devices. [ 24 , 25 , 26 , 27 , 28 , 29 ] Recently, significant improvements have been achieved in high performance organic solar‐blind photodetectors, either by interface engineering or by developing novel device architectures, and so on.…”

2D Ultrawide Bandgap Semiconductors: Odyssey and Challenges

“…

Over the past decades, UWBG semiconductors employed in (opto)electronics are dominated by the traditional bulk materials, which have been extensively investigated and widely commercialized, such as Ga 2 O 3 , [1][2][3][4] diamond, [5][6][7] Mg x Zn 1-x O, [8] indium tin oxide (ITO), [9] indium gallium zinc oxide (IGZO), [10] III-nitride (GaN, AlN, Al x Ga 1-x N). [11] Furthermore, various methods have been used to improve devices performance via extensive research efforts, such as localized surface plasmon, [12,13] bandgap engineering, [14,15] array, [16][17][18] heterojunction. [19][20][21][22][23] However, in the post-Moore era, the traditional UWBG semiconductor devices with large size, high power and high cost cannot meet the future requirements of high-performance (opto)electronic devices.

…”