利用氣相砷化鍺擴散誘發混和製程製做背脊-隱埋式波導混合結構之808奈米雷射二極體

我們利用砷化鍺粉末再加上額外的砷放置於石英安瓿中，在p型及semi-insulating砷化鎵基板上進行n型參雜的氣相鍺擴散；並透過光致發頻譜發現一寬頻訊號(0.86 電子伏特~1.38電子伏特)，推測其來源為GeGa-VGa自我激發中心(self-activated center, SA center)與鄰近的鍺-氧缺陷複合體。其中，氧主要來自表面帶有氧化鍺的砷化鍺粉末與氧化砷蒸氣分子反應的副產物。因為共同參雜了氧和鍺，我們透過變溫光致發頻譜觀察到與文獻已知的自我激發中心頻譜訊號產生位移(從1.2電子伏特到1.1電子伏特)，也增加了其振動能，而其熱活化能約為150電子毫伏-180電子毫伏。除了基本的材料分析之外，接著利用上述的氣相鍺擴散造成在外圍波導及鏡面區域的量子井混合方式，本實驗製做出砷化鎵系統的808-奈米雷射二極體，其結構為背脊式波導與埋隱式量子井異質結構的綜合體。透過對電流-電壓的一次及二次微分計算(DIV technique)，可以定量地計算串聯電阻、並聯漏電及導通電壓，並得到如下結果：810 oC, 10小時的鍺擴散可以有效降低螺紋狀差排網絡造成的並聯漏電；然而另一方面，熱處理也降低量子井效率並使得試片中做為參雜的鋅及碳原子重新分佈，造成接面的位移，進而降低了內部量子效益、提升了閾值電流及降低斜率效率(從1.046 瓦/安培到0.382 瓦/安培)。然而鍺誘發形成的背脊式波導與埋隱式量子井異質結構綜合體結構，提升了斜率效益(0.833 瓦/安培)；並更重要地，由於非吸收鏡面而提升了光學災難性損傷功率，從未做任何退火的3.4 瓦提升至4.6 瓦，改進幅度約34 %。

關鍵字

鍺擴散；漏電流；雷射二極體

並列摘要

The germanium diffusion of n-type doping in both p-type and semi-insulating bulk GaAs with GeAs powders plus extra arsenic as the vapor source in quartz ampoules has been demonstrated, and a broad peak (0.86-1.38 eV) in photoluminescence has been observed. The broad band is attributed to GeGa-VGa self-activated (SA) centers associated with nearby Ge-O defect complex. The source of oxygen mainly originates from the GeAs powder which contains Ge-O surface oxides and as the oxidation byproducts due to reactions between GeAs and As2O3 vapor molecules. Due to the un-intentional co-incorporation of oxygen, shift in emission peak of the well-documented SA center from 1.2 eV to 1.1 eV with a thermal activation energy of 150-180 meV and increase in the vibrational energy of the defect complex are observed. In addition to basic materials study, GaAs-based 808-nm laser diodes have been fabricated with a hybrid structure of ridge-waveguide/buried quantum well heterostructure (QWH) by employing vapor phase GeAs diffusion to induce quantum well intermixing (QWI) both in the waveguide region and near the facet area. Quantitative assessment of series resistance, shunt leakage and turn-on voltage has been made through evaluating first and second derivatives of I-V characteristics (DIV technique). Results indicate that shunt leakage attributed to the existence of threading dislocation networks can be greatly suppressed in Ge-diffused samples (810 oC for 10 hours). On the other hand, heat treatment causes thermal degradation of QW and dopant redistribution of Zn and carbon leading to loss of internal quantum efficiency and deterioration of laser threshold current and slope efficiency from 1.046 W/A to 0.382 W/A due to junction migration. Formation of the ridge/buried-heterostructure with Ge-induced intermixing helps recover the slope efficiency, 0.833W/A, and more importantly improves the catastrophic-optical damage (COD) power by 34% from 3.4 W for as-grown samples to 4.6 W, which is attributed to non-absorbing mirror effect.

並列關鍵字

germanium diffusion ； leakage current ； laser diode

參考文獻

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利用氣相砷化鍺擴散誘發混和製程製做背脊-隱埋式波導混合結構之808奈米雷射二極體

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