a-Si:H热处理过程中形成的纳米硅粒及其光致发光

报道了氢化非晶硅薄膜在600～620℃温度下快速退火10 s可以形成纳米晶硅,其拉曼散射表明,所形成的纳米晶硅在薄膜中的分布是随机的,其直径在1.6～15 nm内.根据晶体生长理论和计算机模拟,讨论了升温快慢与所形成纳米硅颗粒大小之间的关系,并且在强光照射下观察了纳米晶硅在薄膜中的结晶和生长情况.经退火形成的nc-Si可见光辐射较弱,不能检测到它们的光致发光,但用氢氟酸腐蚀钝化后则可检测到较强的红PL,并且钝化后的nc-Si在空气中暴露一定时间后,其辐射光波长产生了蓝移.就表面钝化和量子限制对可见光辐射的重要性作了讨论.

The nanocrystalline silicon clusters formed in thermally annealed a-Si:H films and the potoluminescence

Nanocrystalline silicon(nc-Si) clusters can be formed by rapid thermal annealing the hydrogenated amorphous silicon (a-Si:H)films at 600℃-620℃ for about 10 s. Characterized by micro-Raman scattering, the formed nc-Si clusters are randomly distributed in the amorphous matrix of the annealed films with their sizes in the range of 1.6-15 nm in diameter. Under high power laser irradiation, in situ nanocrystallization and subsequent nc-Si growth in the a-Si:Hfilms have been demonstrated. Based on the theory of crystal nucleation and growth, the effect temperature ramp rate on the sizes of the formed silicon particles is discussed. Under high power laser irradiation, in situ nanocrystallization and subsequent ncSi clusters are small enough for visible light emission, authors have not detected any visible photolum inescence (PL) from these nc-Si clusters before surface passivation. After electrochemical oxidization in hydrofluoric acid, however, intense red PL has been detected. Cyclic hydrofluoric oxidization and air exposure can cause subsequent blue shift in the red emission．The importance of surface passivation and quantum confinement in the visible emissions has been discussed.