Electrical and Optical Properties of FeSi₂ Layers

Abstract

We fabricated ox-FeSi 2 and 13-FeSi 2 layers by using two methods: Ion Beam Synthesis (IBS) and Molecular Beam Allotaxy (MBA). In the latter technique a trapezoidal-shaped Fe profile was embedded in the Si matrix by codeposition of Si and Fe at temperatures of about 650TC. A rapid thermal anneal of the IBS and MBA samples at 1150'C for 10 s is necessary to obtain continuous a-FeSi 2 layers. The Fe vacancy concentration of the a-FeSi 2 layers was varied by a further anneal at lower temperatures. Resistivity measurements indicate a decrease of the resistivity with decreasing Fe vacancy concentration. The a-FeSi 2 was transformed to a continuous rl-FeSi 2 layer by an anneal at 800'C for several hours. To investigate the nature of the band gap we performed absorption measurements at room temperature and 77 K. The analysis of the room temperature data revealed a direct transition at 0.84 eV and an additional indirect transition at 0.78 eV. At 77 K the direct transition shifts to -0.875 eV and the indirect to -0.86 eV.

Electronic structure and X-ray spectral characteristics of the semiconductor and metal phases of iron disilicide

“…The magnetic moment of α-FeSi 2 is missing, which is consistent with the results of our earlier calculation [35]. The estimated width of the band gap for indirect transitions β-FeSi 2 was 0.78 eV, for direct transitions -0.83 eV, which corresponds to the hundredths of the values given in the Table 3 experimental values [36,37] and means that the semiconductor is indirect-gap [38].…”

“…The estimated width of the band gap for indirect transitions β-FeSi 2 was 0.78 eV, for direct ones -0.83 eV, which corresponds to the hundredths of the values given in the Table . 3 experimental values [36,37] and means that the semiconductor is non-direct-band [38].…”

Structural and electronic properties ofβ-FeSi2nanoparticles: The role of stacking fault domains

“…Furthermore, β-FeSi 2 is nontoxic, consists of elements that are abundant in nature, and is compatible with existing silicon-based technology [1]. Optical experiments have revealed indirect and direct band gaps of 0.78 eV and 0.84 eV, respectively [2]. An absorption coefficient α of above 10 5 cm −1 has been reported for β-FeSi 2 thin films [3].…”

Электронная Структура И Рентгеноспектральные Характеристики Полупроводниковой И Металлической Фаз Дисилицида Железа

“…Расчетная ширина запрещенной зоны для непрямых переходов β-FeSi 2 составила 0.78 eV, для прямых -0.83 eV, что с точностью до сотых соответствует приведенным в табл. 3 экспериментальным значениям [36,37] и означает, что полупроводник является непрямозонным [38]. Рассчитанная нами ширина валентной зоны β-FeSi 2 составила 13.41 eV, а ее минимум находится в центре (точка Ŵ) первой зоны Бриллюэна.…”