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采用直流磁控溅射方法在不同的氩气-氮气(Ar-N2)气氛中制备了非晶氮化镓(a-GaN)薄膜.X射线衍射分析(XRD)和拉曼光谱(Raman)表明薄膜具有非晶结构.通过椭偏光谱(SE)得到薄膜的折射率和厚度都随着氩气分量的增多而增大.紫外—可见光谱(UV-Vis)的测量得到,当氩气分量R,即Ar/(Ar+N2),为0%时,薄膜的光学带隙为3.90eV,比晶体GaN(c-GaN)的较大,这主要是由非晶结构中原子无序性造成的;而当R增大时(10%—40%),薄膜的光学带隙降低为2.80—3.30eV,这可能是由于薄膜中存在未成键Ga原子引起的.对吸收带尾进行了拟合,得到在高能量和低能量范围的带尾态特征能量分别为0.257—0.338eV和1.44—1.89eV,表明a-GaN具有比c-GaN更宽的带尾态.在室温光致发光(PL)谱中,360nm处的发光峰来源于带间发射.
Amorphous gallium nitride (a-GaN) films were prepared by DC magnetron sputtering in different Ar-N2 atmospheres.X-ray diffraction (XRD) and Raman spectroscopy The film has an amorphous structure.The refractive index and the thickness of the film obtained by ellipsometry (SE) both increase with the increase of the argon component.The UV-Vis spectrum is measured, and when the argon component R (Ar / (Ar + N2)) is 0%, the optical band gap of the film is 3.90eV, which is larger than the crystalline GaN (c-GaN), which is mainly caused by the disorder of the atoms in the amorphous structure While the optical bandgap of the film decreases to 2.80-3.30eV when R increases (10% -40%), which may be caused by the presence of unbonded Ga atoms in the film. The tail of the absorption band is fitted, The tail-band energies at high energy and low energy range were 0.257-0.338eV and 1.44-1.89eV, respectively, indicating that a-GaN has a wider band tail state than c-GaN. At room temperature photoluminescence (PL) In the spectrum, the luminescence peak at 360 nm originates from the interband emission.