一維與二維電激發光子晶體面射型雷射之研究

Abstract

於本篇論文中，我們鋪上金屬電極首先改善L-I曲線的震盪行為。並在同時發現金屬電極對於雷射特性的影響。當我們將電極光窗設計在結構上時，將大幅提高雷射閾值。但是將金屬電極遠離結構後，可以得到折衷方案雷射閾值從230mA下降至28mA和沒上金屬電極前(20mA)相去不遠。 接著我們再利用這樣的方式將光子晶體的結構從一為改成二維並成功製作出具有二維光子晶體結構的樣品。在相同寬度條件下比較一維與二維兩者的各種雷射特性，結果發現在這樣大長寬比的平台結構中，二維的雷射閾值較高(50mA)，且發散角(1.9o,9.7o)與一維(1.4o,10.4o)相比差異不會太大。利用模擬軟體COMSOL，我們可以看出在這樣大長寬比的結構中，二維Q值(297)遠小於一維Q值(10817)且場型分布在長方向上較短寬度方向上較長，可以對應到遠場量測到的發散角有著相似於傅立葉轉換的關係。這是因為二維在這樣的大的長寬比結構中，在其中一個方向上無法有效發揮二維的耦合特性。而兩者的溫度變化特性用紅移量(131oC與121oC)與T0來觀察幾乎一樣，也就是說溫度特性是由發光材料本身所造成，與光子晶體的圖形與維度無太大關係。 在最後我們一步步優化光晶條件，首先改變蝕刻深度，使的光激發能夠實現。接著製作不同的電流侷限結構並比較兩者在發光情形上的差異，結果發現具有侷限結構的元件有較佳的電流分布。在未來的實驗中，希望能夠先模擬出電流路徑，在模擬載子復合的發光位置在光子晶體平面上不同位置會造成影響，藉此完整了解電激發的行為。

In this paper, we first covered the metal contact to improve the L-I curve of the oscillation behavior. And at the same time found that the impact of metal contact on the laser characteristics. When we covered the metal contact with aperture on the structure, will greatly increase the laser threshold. However, after the metal contact away from the structure, this way can get a compromise laser threshold from 230mA down to 28mA and is not far from the sample with no metal contact(20mA). Then we use this way to the structure of the photonic crystal from 1D to 2D and successfully produced the 2D PhC sample. It is found that in the platform structure with such a large aspect ratio, the 2D laser threshold is higher (50mA) and the divergence angle (1.9o, 9.7o) is similar to the 1D laser(1.4o, 10.4o). Using the simulation software COMSOL, we can see that the 2D Q value (297) is much smaller than the 1D Q value (10817) in the structure with such a large aspect ratio, and the field distribution is longer in the shorter width-direction , this simulation result indicated that the divergence angle corresponding to the far-field measurement has a relationship similar to the Fourier transform from near field. This is because the 2D structure in such a large aspect ratio, in which one direction can not effectively play 2D coupling characteristics. (131oC and 121oC) and T0 to observe almost the same, that is the temperature characteristics caused by the luminescent material itself, and the photonic crystal structure and dimensions are not much relationship. In the end we optimize the crystal conditions step by step, first change the etching depth, so that the optical excitation can be achieved. Then different current confinement structures were fabricated and compared. The device with current confine aperture has better current spreading situation. In the future work, we hope to simulate the current path and setting the light source at difference position in the PhC strudture. This can help ue understand the complete electrically pumped luminescence.