Font Size: a A A

Preparation Of Gallium Nitride Nanowire And Its Detector Using Nitrogen Doped Gallium Oxide Film As Underlayer

Posted on:2016-07-30Degree:DoctorType:Dissertation
Country:ChinaCandidate:R SunFull Text:PDF
GTID:1108330503969757Subject:Materials science
Abstract/Summary:PDF Full Text Request
Gallium nitride(Ga N) nanowires, a kind of typical wide band gap semiconductor nanomaterials, not only have the excellent optoelectrical properties of Ga N bulk material, but also possess the characteristics of nanomaterials. Ga N nanowires can be widely used in the field of nano-optoelectronic devices, such as lasers, light-emitting diodes, ultraviolet detectors and field-effect transistors, etc. However, there are still many problems to be solved in preparation, such as catalyst contamination, high production cost and complex method, which seriously limit the quality and applications of Ga N nanowires. In this dissertation, Ga N nanowires with no catalysts were synthesized using nitrogen-doped gallium oxide(Ga2O3) film as underlayer. The Ga N nanowires were also used to prepare the metal-semiconductor-metal(MSM) ultraviolet(UV) detector.The main contents of this dissertation are as follows. High quality nitrogen-doped Ga2O3 films were prepared by magnetron sputtering method on sapphire(0001) substrates. Various preparation parameters, including sputtering pressure, nitrogen flow(N2), film thickness and annealing atmosphere, were investigated for their effects on the surface morphologies, structure characteristics and optical properties of nitrogen-doped Ga2O3 films in details. Ga N nanowires were synthesized through an underlayer of nitrogen-doped Ga2O3 films by chemical vapor deposition(CVD). Preparation parameters, including growth temperature and ammonia(NH3) flow, were studied for their effects on the surface morphologies, Raman and luminescence properties of Ga N nanowires. The MSM type UV detector based on Ga N nanowires was prepared. The characteristics of the UV detector were also analyzed.The study on the preparation of nitrogen-doped Ga2O3 films by magnetron sputtering method showed that the surface of nitrogen-doped Ga2O3 films was very smooth, and the Ra was all less than 3 nm. The nitrogen-doped Ga2O3 films were the monoclinic structure. The crystalline properties of nitrogen-doped Ga2O3 films were firstly improved with the increase of sputtering pressure, N2 flow rate and film thickness, but then become poor. The nitrogen-doped Ga2O3 films exhibited good optical quality, and the average transmittance exceeded 80% in the visible range of 400800 nm. The optical band gap increased with the increase of sputtering pressure, but decreased with the increase of N2 flow rate and film thickness. The crystalline properties of nitrogen-doped Ga2O3 films were improved after annealing in N2, O2 and Air at 800 oC, respectively. The average transmittance in the visible range was increased to 85%.The study on the preparation of Ga N nanowires using nitrogen-doped gallium oxide(Ga2O3) film as underlayer showed that the surface morphology of Ga N nanostructures was varied from one-dimension nanowires to micro-grains with the increase of growth temperature from 850 oC to 1000 oC. The average diameter of Ga N nanowires decreased with the decrease of NH3 flow rate from 160 sccm to 80 sccm. The Ga N nanowires showed tensile stress, and the tensile stress decreased with the decrease of NH3 flow rate. The photoluminescence(PL) spectra were composed of a strong ultraviolet emission peak(365 nm) and a yellow luminescence peak(590 nm).The study on the UV detector based on Ga N nanowires showed that the UV detector had a photocurrent of 2.4×10-4 A and a dark current of 2.3×10-6 A at 5 V. Compared with the UV detector based on Ga N film, the 92 times larger photocurrent was observed from the detector based on Ga N nanowires, and the dark current was also significantly increased. The detector based on Ga N nanowires had a higher responsivity and a lager UV-to-visible rejection ratio, and the responsivity and detectivity were 2.52 A/W and 1.17×1012 cm·Hz1/2·W-1 at 360 nm, respectively. The quantum efficiency of the detector based on Ga N nanowires was larger than 100%, which indicated that there existed a large photoconductive gain for the detector. The ultraviolet detector based on Ga N nanowires had a reproducible and stable transient response, and the response time was about 22 μs.
Keywords/Search Tags:Ga2O3 films, GaN nanowires, magnetron sputtering, chemical vapor deposition, ultraviolet detectors
PDF Full Text Request
Related items