Wen Jie, Chen Ting, Ran Guang-Zhao
School of Physics, State Key Laboratory for Mesoscopic Physics, Peking University, Beijing 100871, China.
Guang Pu Xue Yu Guang Pu Fen Xi. 2009 Jul;29(7):1736-9.
Recently, a monolithic integration of optics and electronics in a single Si chip has attracted a great deal of attention due to its attractive application prospects: the potential for forming high speeded information processing and transmission, and inexpensive and low power silicon chip. Developing high-efficiency silicon-based light sources is the main task in silicon photonics. In the present paper the authors explore a potential way for silicon-based light-emitting application. A Mn(2+)-activated silicon-rich silicon oxide (SiO2 : Si : Mn2+) film was prepared on the n(+)-type silicon substrate using co-sputtering technique followed by doping and activation of Mn with a thermal diffusion method. High-resolution transmission electronic microscope study shows that the film is embedded with 3-5 nm silicon nanocrystals. Bright green photoluminescence (PL) from the film was observed under ultraviolet radiation and peaked at 524 nm (2.36 eV), the decay time of which is 0.8 ms. It is generally believed that the green radiation originates from 4T1 --> 6A1 transition in Mn2+. The PL excitation spectrum of the film, monitored at 524 nm, has a peak of 254 nm, similar to that of the Zn2 SiO4 : Mn film. It is believed that the strong 254 nm absorption is attributed to Mn2+ --> Mn3+ ionization or ds --> d4s transition. A very broad electroluminescence spectrum ranging from 400 to 800 nm, covering almost the whole visible band, was observed from the device made of the SiO2 : Si : Mn2+ film at low reverse biases. The threshold voltage of the device is as low as 5 V. Spectra of the device demonstrate that the electroluminescence is attributed to Mn2+ and luminescence centers in the Si-rich SiO2 film. The authors interpret that Mn2+ excitation is mainly due to direct impact excitation of hot electrons, silicon nanocrystals in the SiO2 film help electrons tunnel from a silicon nanocrystal to an adjacent one, and are advantageous for generating hot electrons to excite Mn2+.
近来，光学与电子学在单个硅芯片上的单片集成因其诱人的应用前景而备受关注：具备形成高速信息处理与传输的潜力，以及廉价且低功耗的硅芯片。开发高效的硅基光源是硅光子学的主要任务。在本文中，作者探索了一种硅基发光应用的潜在途径。采用共溅射技术在n⁺型硅衬底上制备了Mn(2⁺)激活的富硅氧化硅（SiO₂ : Si : Mn²⁺）薄膜，随后通过热扩散法对Mn进行掺杂和激活。高分辨率透射电子显微镜研究表明，该薄膜中嵌入了3 - 5纳米的硅纳米晶体。在紫外辐射下观察到该薄膜发出亮绿色光致发光（PL），峰值位于524纳米（2.36电子伏特），其衰减时间为0.8毫秒。一般认为，绿色辐射源于Mn²⁺中的⁴T₁→⁶A₁跃迁。该薄膜在524纳米处监测的PL激发光谱在254纳米处有一个峰值，与Zn₂SiO₄ : Mn薄膜的类似。据信，254纳米处的强吸收归因于Mn²⁺→Mn³⁺电离或ds→d4s跃迁。在低反向偏压下，从由SiO₂ : Si : Mn²⁺薄膜制成的器件中观察到了范围从400到800纳米、几乎覆盖整个可见光波段的非常宽的电致发光光谱。该器件的阈值电压低至5伏。器件的光谱表明，电致发光归因于Mn²⁺以及富硅SiO₂薄膜中的发光中心。作者解释说，Mn²⁺的激发主要是由于热电子的直接碰撞激发，SiO₂薄膜中的硅纳米晶体有助于电子从一个硅纳米晶体隧穿到相邻的硅纳米晶体，并有利于产生热电子来激发Mn²⁺。
