| Solar-blind ultraviolet photodetectors(PDs),which can detect signals in the deep ultraviolet range from 200 to 280 nm without being affected by the background of the sunlight,have a vast and growing number of military and civil surveillance applications in missile tracking,fire detection,ozone holes monitoring,chemical/biological analysis,and so on.For semiconductor alloys,it is known that high quality epitaxial AlGaN film is difficult to be prepared due to high growth temperature and single wurtzite phase ZnMgO cannot be used to detect entire deep ultraviolet region due to their mismatched bandgaps.Recently,based on monoclinic gallium oxide(?-Ga2O3)has been widely investigated due to its suitable bandgap of?4.9 eV.Meanwhile,the corresponding absorption wavelength of ?-Ga2O3 is 253 nm,which has a very high photoelectric response in the ultraviolet region and can be used to prepare high-performance solar-blind photodetectors array.In this work,highly integrated metal-semiconductor-metal structured photodetectors arrays of 16×16,8×8 and 4×4 have been designed and fabricated for the first time.It can do some basic work for the development and application of high-performance solar-blind photodetectors array with broad application prospects.The main research results are as follows:(1)The ?-Ga2O3 thin films were deposited by radio frequency magnetron sputtering.A two-inch(0001)Al2O3 substrate cleaned by the standard Radio Corporation of America process was used as a starting substrate.And the prepared film grows preferentially along the(201)crystal plane.The high pure argon was admitted up to the pressure of 1 Pa.The growth temperature was set at 750? and the power applied to the Ga2O3 target was fixed at?80 W.(2)In this paper,the photodetector arrays we designed are implemented on one side of the thin film.There is no need to make a micro-bridge structure on the back of the substrate,nor need to dig isolation trenches to fill the insulating material.When the array reaches a certain scale,the direction of the wire is simple,without the contradiction between the lead and the duty ratio of the element.At the same time,the structure of array guarantees the detection system with a high responsivity,and the response speed of each photodetector cell was fast enough,followed by the uniformity of array element.The short circuit of one photodetector cell will not affect the performance of the surrounding detector.(3)The final photodetectors arrays were made by sequentially transferring the features from each mask,level by level,to the surface of the?-Ga2O3 thin films.Ti/Au are selected as the metal electrode materials,Al2O3 was used as the oxide insulating layer material,and the prepared arrays were packaged with ceramic packagers to obtain ?-Ga2O3-based solar blind ultraviolet photodetector arrays.,It was found that every photodetector cell is sensitive to ultraviolet light of 254 nm and has a large photocurrents,exhibiting good spectral selectivity.And the dark current of all photodetector units is very low.The detector has good sensitivity,good stability and repeatability.The photo responsivity is 8.926 × 10-1 A/W@250 nm at a 10 V bias voltage,and the deep ultraviolet(DUV)-to-visible discrimination ratio(250 nm to 400 nm)is 905.All of photodetector cells exhibit the solar-blind ultraviolet photoelectric characteristic and the consistent photo responsivity with a standard deviation of 12.1%.The outcome of the study offers an efficient route toward the development of high-performance and low-cost DUV photodetector arrays. |
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