Fully Transparent and High‐Performance ε‐Ga₂O₃ Photodetector Arrays for Solar‐Blind Imaging and Deep‐Ultraviolet Communication

Abstract

During the past decade, due to extensive application in modern industrial agriculture and military intelligence integration development, transistors, [1] photodetectors, [2] light-emitting diodes, [3] and other power electronics have attracted widespread research. [4,5] Photodetectors are photoelectronic devices that convert optical signals (UV-IR) into electrical signals. The emergence of wide bandgap semiconductors has resulted in solar-blind deepultraviolet (SBDU) photodetectors (PDs) with extremely low background noise receiving considerable attention. [6,7] In general, SBDU PDs are constructed of semiconductor materials with a bandwidth greater than 4.4 eV, including Al x Ga xÀ1 N, [8] ZnMgO, [9] SiC, [10] Ga 2 O 3 , [11][12][13] and diamond. [14] A new type of ultra-wide band semiconductor material, Ga 2 O 3 with a wide bandgap of %4.9 eV, does not require a complex alloying process and possesses high chemical stability, and can therefore be considered a natural material for solar-blind signals detection. To date, various types of Ga 2 O 3 -based PDs have been proposed, including p-n junctions, [15] heterojunctions, [16,17] Schottky diodes, [18] avalanches, [19] metal-semiconductor-metal (MSM) [20,21] and photoelectrochemical [22] PDs. Among them, MSM-type SBDU PDs have been widely studied as their preparation is simple and they are easily integrated with electronic devices. Moreover, MSMtype Ga 2 O 3 -based PDs maintain a high performance with a low dark current, large light-to-dark ratio, excellent responsivity, and a fast photoresponse time. [23] These high-performance and easyto-integrate MSM-type Ga 2 O 3 -based PDs present great potential in civil and military applications, including medical imaging, secure optical communication, environmental and fire monitoring, space exploration, and high-voltage leakage detection. [24][25][26] As early as 2018, Chen et al. prepared an MSM-type β-Ga 2 O 3 film-based PD array (4 Â 4) to obtain clear target images in solar-blind imaging. [27] When the bias voltage is 45 V, the peak responsivity and detectivity of the PD array unit are %12.4 A W À1 and 1.9 Â 10 12 Jones, respectively. Recently, Qian et al. fabricated a large-scale high-uniformity 32 Â 32 image sensor array, based

Review of β-Ga2O3 solar-blind ultraviolet photodetector: growth, device, and application

“…Till now, there are two approaches to achieve imaging: the imaging based on a single PD which can be achieved by scanning object [136]. And the one-time imaging based on the PD array [137][138][139][140][141][142]. The comparison of them was briefly summarized in table 6.…”

Multi-pixels gallium oxide UV detector array and optoelectronic applications

“…In addition, the interface defect density and trap density of states can be reduced by means of interface engineering and surface modification, which is helpful to improve the response speed of the array. Alternatively, transparent conductive materials [55] can be used to enhance the transmission of light and the injection efficiency of charge carriers, or adopting an electrode structure with a larger effective contact area and shorter carrier transport path can reduce the impedance of the electrode thin film interface and improve the injection and transport speed of carriers.…”

“…To overcome these limitations, researchers have been exploring and developing novel electrode materials that are transparent, flexible, and highly conductive, aiming to drive the development of the next generation of optoelectronic devices. Therefore, Zhou et al [55] designed a full-transparent MSMtype solar-blind detection array using indium tin oxide (ITO), indium gallium zinc oxide (IGZO), and aluminum zinc oxide other reported imaging-capable cases are shown in table 2). And it can easily know that a small array scale is extremely unfavorable for imaging complex structures.…”

“…In addition to being used for ultra-sensitive deep-ultraviolet (DUV) photodetection, photodetector array can also be used in other optical applications shows in figure 1. And these optical applications of array are based on its fundamental function of optical detection for epitaxial expansion, such as UV imaging [54], UV Communication [55] and so on. However, research on Ga 2 O 3 photodetector array is still in its early stages, and the reported arrays still have many shortcomings, such as a small number of photodetector array units, single and unoptimized array structure, low area utilization due to large unit area, poor micromachining technology, and immature array growth technology.…”

Study on PECVD-hetero-grown β-Ga2O3 thin film and temperature-modulated solar-blind UV photodetection

“…Benefiting from the high immunity to * Authors to whom any correspondence should be addressed. environmental disturbances of the solar-blind UV PD, it can be utilized to carry out UV communication [10,11], imaging [12,13], and flame sensing [14], etc, showing superb photodetection performances. Most of the current Ga 2 O 3 -based solar blind detectors use Ga 2 O 3 thin films for simplicity and low cost of preparation, and high-quality epitaxial films of Ga 2 O 3 are essential for the design and fabrication of Ga 2 O 3based devices [15][16][17].…”