Study on GaN-based blue vertical cavity surface emitting laser on Si

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GaN, AlN and their alloys have direct transition type band gap structure and have attracted much attention for optical devices in the blue-ultraviolet region. GaN-based edge emitting lasers have been extensively studies and have achieved room temperature continuous wave operation. Recently, GaN-based vertical cavity surface emitting lasers (VCSELs) with a distributed Bragg reflector (DBR) have attracted much interest for various optical applications due to the fabrication of a smooth mirror without a cleavage technique. The DBR is also effective in improving the output power of LED. Thus, the DBR plays an important rule to fabricate high performance optical devices such as LED and VCSEL. In this study, the use of the GaN/AlィイD20.27ィエD2GィイD20.73ィエD2 DBR as a bottom mirror has improved the characteristics of InGaN MQW LED sapphire. Moreover, the reflectivity as high as 98% has been obtained by the use of the strained layer superlattice (SLS) beneath the DBR structure. The InGaN MQW LED grown on the 15 pairs of DBR with a reflectivity of 75% was fabricated for the first time to the best of our knowledge. The output power of 120μW at 435 nm was about 1.5 times as large as that of the conventional LED. The DBR is very promising for the fabrication of high performance GaN-based LED and VCSEL.