National High Technology Research and Development Program of China [2006AA03Z409]; National Science Foundation of China [60876007, 10974165]; Xiamen Municipal Science & Technology Bureau [2006AA03Z110]InGaN based light emitting devices (LEDs) with asymmetric coupled quantum wells (AS-QWs) and conventional symmetric coupled quantum wells (CS-QWs) active structures were grown by metal-organic chemical vapor deposition technique. The LEDs with AS-QWs active region show improved light emission intensity and reduced forward voltage compared with LEDs with CS-QWs active region. Based on the electroluminescence measurements and the devices structure analysis, it can be concluded that these improvements are mainly attributed to the efficient hole tunneling through barriers and consequently the uniform distribution of carriers in the AS-QWs. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3254232
We have fabricated and characterized GaN-based vertical cavity surface emitting lasers (VCSELs) with a unique active region structure, in which three sets of InGaN asymmetric coupled quantum wells are placed in a half-wavelength (0.5λ) length. Lasing action was achieved under optical pumping at room temperature with a threshold pumping energy density of about 6.5mJ∕cm2. The laser emitted a blue light at 449.5nm with a narrow linewidth below 0.1nm and had a high spontaneous emission factor of about 3.0×10−2. The results indicate that this active region structure is useful in reducing the process difficulties and improving the threshold characteristics of GaN-based VCSELs.
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