Surface photovoltage spectroscopy and photoluminescence study of stacked self-assembled InAs/GaAs quantum dots

• Main Authors: Chen Huai-Shenq, 陳輝勝
• Other Authors: Huang Ying-Sheng
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/23474547095652970939

碩士 === 國立臺灣科技大學 === 電子工程系 === 92 === We present a systematic study of four 30-layer stacks of molecular beam epitaxially grown self-assembled InAs quantum dots （QDs）with GaAs spacer layer thickness of 10,15,20, and 30nm, respectively, using surface photovoltage spectroscopy（SPS）and photoluminescence（PL）.The SPS signals, observed from all the relevant portions of the samples including the QDs and wetting layer, originated from the spatial separation of photogenerated carriers and their subsequent movement to the top and bottom sides of the samples under the surface electric field. Both the SPS and PL measurements show a systematic increasing blue shift of the QD related signals with spacer thickness varying from 30nm to 10nm,while the PL spectrum for 30nm spacer looks very similar to that of a reference sample with only one InAs dot layer. The blue shift of the QD related signals has been attributed to the strain-induced effects on the formation of InAs QDs in GaAs and in the case of 30nm spacer layer sample,total strain relief causes the QD nucleation without any influence of the first dot layer. This study demonstrates the considerable potential of SPS and PL for the contactless and nondestructive characterization of QDs structures.