2007-08-012024-05-18https://scholars.lib.ntu.edu.tw/handle/123456789/713094摘要：隨著顯示科技和照明需求的發展，白光發光二極體已經漸漸成為目前發展的重點。由於發光二極體有體積小以及其理論上高效率之優點， 目前漸漸已經使用在液晶螢幕的背光模組以及一些固態照明的領域上；然而，目前以三五族氮化銦鎵之發光二極體， 有兩個極為明顯的缺點尚未解決。首先其綠光二極體的發光效率仍然不理想。另外，當電流增加時，其發光效率有很明顯的減少情形。 在本計畫裡，我們會建立適當數值分析模型來分析氮化物之量子井和量子點發光二極體， 我們計畫發展的分析模型裡將會完整的考慮載子的流動分析，電子和電洞的發光, 激子的產生, 晶格內部應力之影響, 極化效應, 和能帶結構之修正。在接觸接面的流入效率， 載子在半導體內部的流動的特性上，我們會發展計算一維到三維的 Poisson 方程式和 Drift-diffusion 方程，並且利用蒙地卡羅 (Monte Carlo) 的方法，來分析載子比較真實的流動情形；另外， 針對量子井和量子點其能帶結構之計算和所受到應力形變之影響，我們會發展 k.p 的方法來計算其一維到三維元件之能帶結構，並分析極化效應所造成的影響。 在本計劃裡, 我們會考慮利用在異位接面和極化效應的一些結構特性來增進輻射通道 (radiative channel) 和壓制非輻射 (non-radiative) 通道, 經由小心的異位結構界面的設計，我們希望能夠促進其光激子留在輻射通道，而極化效應所產生的極性電荷則可以利用來促進電洞的產生， 和降低歐姆接觸電阻。而量子點之特性，能夠將電子電洞 對侷限在較小的範圍內，因此能夠降低其輻射結合之時間, 並增進發光效率。因此我們會研究量子點在不同的應力下的穩定態， 以及其發光頻譜和量子點結構之關係。傳統上，極化效應被認為是降低發光效率的缺陷。在本計劃裏，我們會設法尋找和利用極化結構的優點來設計其光電元件，進而改進其發光效率。<br> Abstract: White light LEDs have become very important technologies for many applications such as lightening and LCD back light modules. However, LED based lighting systems using III-nitrides suffer from two key shortcomings related to electrical and light efficiency values. These are poor efficiency for green light emission and efficiencies that rapidly degrade at high current injection. In this proposal, we will build up the numerical models for analyzing and designing the nitride based quantum well/dot LEDs. The carrier transport, recombination, strain, and polarization effects of InGaN quantum dot will be fully considered in our model. We will develop several numerical methods to analyze the nitrides LEDs. For the study of carrier injection and transport, we will develop 1D to 3D Poisson and drift-diffusion solver and Monte Carlo based program. We will also develop models to simulate the heating effects due to non-radiative process. For the quantum well, quantum wire(rod), and quantum dot structures, we will develop k.p model and valence force field to calculate the band structure of conduction and valence band and the strain effects in the device. In this proposal, heterostructure design and polar effects are considered for enhancing radiative channels and suppressing non-radiative channels. By careful heterostructure design it should be possible to funnel charge more efficiently into the active radiative region. Polar charges would provide a way to allow better p-doing and better hole injection. Also for the quantum dot structures, it can provide a better carrier confinement and reduce the radiative life time. Therefore, we will study the stable condition of quantum dot under the strain effect and analyze the emission spectrum related the quantum dot size. The polarization effects will also be considered in these models. Currently polar effects do not play a positive role in nitride LEDs since they increase the radiative lifetime and thus can decrease radiative efficiency. In this proposal we will design and test structures that will reduce the present negative aspects of polar fields and instead use polarization for positive impact on LED efficiency.氮化鎵銦化鎵量子井張力量子點白光二極體GaNInNquatum wellquantum dotstrainpolarizationwhite light emitting diodeLEDKp method