低速~(84)Kr~(15+,17+)离子轰击GaAs单晶

用345 keV的Kr15+和340 keV的Kr17+离子以45fi角入射n型GaAs单晶(100)面,测量了表面形貌的变化和发射的375—500 nm Ga I和Kr II的特征光谱线.Krq+(q=15,17)离子轰击后表面形貌的变化主要取决于入射离子的电荷态q.离子沉积到靶表面的能量引起Ga原子激发,其辐射光谱为Ga I 403.2 nm和Ga I 417.0 nm.入射离子中性化过程中俘获GaAs导带电子形成高激发态原子,通过级联退激填充3p,4d等空穴,P壳层电子跃迁发射谱线为Kr II 410.0 nm,Kr II 430.4 nm,Kr II 434.0 nm和Kr II 486.0 nm,Kr II486.0 nm为较强谱线.实验结果表明,入射离子与GaAs单晶相互作用发射的可见光产额与入射离子的电荷态密切相关,较高电荷态Kr17+离子入射产生的光辐射产额大约为Kr15+离子的两倍.

Slow ions 84Kr15+, 17+ bombardment on GaAs

We have investigated surface morphology and visible light emission from slow ions Kr^{15+, 17+} colliding with GaAs (100). The surface disorder of GaAs films mainly depends on the charge state of incident ions. The two spectral lines of target atom Ga belong to transitions of GaⅠ 4p ²P_1/2^o–5s ²S_1/2 at 403.2 nm and 4p ²P_3/2^o–5s ²S_1/2 at 417.0 nm. Light emissions of target species depend on the energy of the incident ions deposited on the target surface atoms. During the neutralization process, the four spectral lines of Kr⁺ respectively can be attributed to the transitions of Kr Ⅱ 4d ⁴F_7/2–5p ²D_5/2^o at 410.0 nm, 5s ²P_3/2–5p ⁴S_3/2^o at 430.4 nm, 5p ⁴D_3/2^o–4d ²D_3/2 at 434.0 nm and Kr Ⅱ 4d ⁴D_1/2–5p ²S_1/2^o at 486.0 nm. They are induced by cascade de-excitation after many electrons of the conductions band of the solid surface captured in highly excited states of the incident ion. Intensities of these six spectral lines from incident ions Kr¹⁷⁺ are obviously larger than Kr^15+'s.
Keywords： surface morphology spectrum highly excited states