Ti-Al共掺杂Si薄膜的光电性能增强机理研究  

Study on the photoelectric performance enhancement mechanism ofTi-Al co-doped Si films

作　　者：陈玉杰 杨洪旺 林宇蓓 邝向军[1] 温才[1] CHEN Yujie;YANG Hongwang;LIN Yubei;KUANG Xiangjun;WEN Cai(School of Mathematics and Physics,Southwest University of Science and Technology,Mianyang 621010,China;School of Materials and Chemistry,Southwest University of Science and Technology,Mianyang 621010,China)

机构地区：[1]西南科技大学数理学院,四川绵阳621010 [2]西南科技大学材料与化学学院,四川绵阳621010

出　　处：《功能材料》2023年第10期10021-10029,10038,共10页Journal of Functional Materials

基　　金：国家自然科学基金项目(51974261);四川省中央引导地方科技发展资金面上项目(2022ZYD0013)。

摘　　要：Ti超掺杂Si(Si:Ti)薄膜是通过脉冲激光的非平衡作用,在Si中掺入超固溶度3个数量级以上的高浓度Ti杂质形成。它摆脱了Si禁带宽度的限制,具有优异的亚带隙近红外(λ=1100~2500 nm)光吸收性能。通过真空电子束蒸发结合紫外纳秒激光熔融的方式,制备了Ti-Al共掺杂Si(Si:(Ti-Al))薄膜,以进一步提高薄膜的亚带隙近红外光吸收性能,更好地满足近红外器件的需求。研究结果表明,Si:(Ti-Al)薄膜的薄层电阻,由本征单晶Si衬底的10^(4)Ω/square量级降低至10^(2)Ω/square量级,与Si:Ti薄膜一致。但是,Si:(Ti-Al)薄膜在亚带隙近红外波段的吸光度,较本征单晶Si衬底平均提高了7倍,最大提高了一个数量级(λ=1800 nm处);较Si:Ti薄膜平均提高了33%,最大提高了57.2%(λ=1200 nm处)。表面形貌分析表明,Si:(Ti-Al)薄膜的二次激光加工降低了表面光反射。薄膜成分分析表明,Si:(Ti-Al)薄膜中存在TiSi_(2)和AlTi。TiSi_(2)的存在表明,Ti杂质被激活后与Si原子键合。AlTi的存在并结合能带结构分析表明,Si:(Ti-Al)薄膜中通过改变Al补偿杂质浓度,调节费米能级位置,从而增强了亚带隙近红外光吸收性能。Ti-hyperdoped Si(Si:Ti)films are formed by doping of Si with a high concentration of Ti impurities,which is three orders of magnitude above the solid solubility limit,via a non-equilibrium effect of pulsed laser.The films get rid of the Si bandgap limit and have an excellent sub-bandgap NIR(λ=1100-2500 nm)light absorption performance.In this paper,Ti-Al co-doped Si(Si:(Ti-Al))films were prepared by vacuum electronbeam evaporation in combination with UV nanosecond laser melting to further improve the sub-bandgap NIR light absorption performance and to better meet the requirement of NIR devices.The results showed that the sheet resistance of Si:(Ti-Al)films was reduced from the order of 10^(4)Ω/square for intrinsic monocrystalline Si substrates to the order of 10^(2)Ω/square,which is consistent with that of Si:Ti films.However,the absorbance of Si:(Ti-Al)films in the sub-bandgap NIR spectra was improved by seven times on average and by an order of magnitude at maximum(atλ=1800 nm)compared to that of the intrinsic monocrystalline Si substrate,and by 33%on average and by 57.2%at maximum(atλ=1200 nm)compared to that of the Si:Ti films.Surface morphology analysis showed that the twice laser processing for Si:(Ti-Al)films reduced the surface reflection of light.The film composition analysis showed that the presence of TiSi_(2) and AlTi in the Si:(Ti-Al)films.The presence of TiSi_(2) indicated that the Ti impurities were activated to bond with Si atoms.The presence of AlTi in combination with the energy-band structure analysis suggested that the Fermi energy level position was controlled by changing in concentration of Al compensated impurities in the Si:(Ti-Al)films,thus enhancing the sub-band gap NIR light absorption performance.

关 键 词：纳秒激光 共掺杂 Si 电学性能 光吸收性能 费米能级 

分 类 号：O472[理学—半导体物理]