Silicon Based Blue Light Emitting Diode

SPIRE最近制造了第一个基于硅的黄色和橙色发光异质结发光二极管(LED)。这些器件是通过沉积透明的n型半导体(铟-半导体)来制造的。二氧化锡)在电化学刻蚀的p型硅片的多孔表面上。可见发射的关键被认为是纳米硅中的量子限制现象多孔硅层中的微晶。随着晶体变小，发射光谱向更短的波长移动(蓝移)。然而，我们注意到发光在黄色以下的硅微晶波长在物理上太脆弱，容易受到环境影响，因此不适合制造器件。对于上述问题，我们提出了独特的解决方案；由于晶体碳(钻石)具有5.47 eV的大带隙，在硅中只有几个百分点的碳的合金会很容易地增加新材料的基带隙到可以制备稳定维度的量子结构的范围。我们将使用非平衡沉积条件来保证Si_(1-x)Cx合金的外延生长没有碳化硅相的形成。在第一阶段，我们将使用化学气相沉积(CVD)工艺在衬底上生长Si1-xCx外延层在低温下进行硅衬底。然后这些层将被电化学刻蚀以产生能够发光的多孔层在蓝色波长范围内。将使用各种表征来评估外延层和多孔层的材料和结构质量技巧。我们将在多孔的Si1-xCx层中展示蓝色光致发光。我们将在第二阶段制作高效率的硅基蓝光LED。

Spire recently fabricated the first yellow and orange- emitting heterojunction light emitting diode (LED) based on silicon. These devices were fabricated by depositing a transparent n-type semiconductor (indium- tinoxide) on the porous surface of electrochemically etched p-type Si wafers. The key to the visible emission is believed to be the quantum confinement phenomenon in the nanometer-sized Si crystallites in the porous Si layers. As crystallites get smaller, the emission spectrum shifts to shorter wavelengths (blue shift). However, we have noted that Si crystallites with light emission below yellow wavelengths are physically too fragile and susceptible to environmental effects and thus are not suitable for device fabrication. We propose a unique solution to the above problem; since crystalline carbon (diamond) has a large band gap of 5.47 eV, alloys of only a few percent C in Si will readily increase the base band gap of the new material into the range where quantum structures of stable dimensionality can be prepared. We shall use non- equilibrium deposition conditions to assure epitaxial growth of Si 1-x Cx alloys without the formation of SiC phase. In Phase I, we will use the chemical vapor deposition (CVD) process to grow epitaxial Si 1-x Cx layers on Si substrates at low temperatures. These layers will then be electrochemically etched to produce porous layers capable of light emission in the blue wavelength range. The material and structural quality of the epitaxial and porous layers will be evaluated using various characterization techniques. The blue photoluminescence in porous Si 1-x Cx layers will be demonstrated. We will fabricate high efficiency Si- based blue LEDs in Phase II.