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Effect Of The AlGaN Electron Blocking Layer On The Performance Of Green Light-emitting Diodes

Posted on:2013-03-30Degree:MasterType:Thesis
Country:ChinaCandidate:M L CengFull Text:PDF
GTID:2248330374990495Subject:Microelectronics and Solid State Electronics
Abstract/Summary:PDF Full Text Request
In recent years, there has been large progress in the blue and green lightGaN-based light-emitting diodes (LEDs), which are attracting great interest as backlight unit, automotive headlights, and general illumination, because of their highefficiency, low energy consumption, long lifetime, small size, and low toxic. Althoughsignificant progress in GaN-based LEDs on sapphire has been made, higherefficiencies and light output are necessary to penetrate the general illuminationmarket. Improving the light output in GaN-based light-emitting diodes have recentlyreceived considerable attention.The green LED epi-wafers used in this work were grown on2inch c-plane (0001)oriented flat sapphire substrates by metal-organic chemical vapor deposition(MOCVD) in a Veeco K465i reactor system. After the process of growing the LEDstructures, the processed wafers were thinned down to90μm for dicing into separatechips with a dimension of178×229μm~2. The effect of n-type AlGaNelectron-blocking layer and p-type AlGaN electron-blocking layer on the the luminousefficiency and light output power of GaN-based LEDs is investigated respectively.The main research work and results are as follows:1. With a n-type AlGaN layer called electron blocking layer (EBL) insertedbetween the n-type GaN layer and the InGaN/GaN multiquantum well (MQW) activeregion, the emission properties of GaN-based LEDs has been investigated. When theinjection current is20mA, the emission intensity of green GaN-based LEDs with90nm n-AlGaN layer is305.2mcd. Compared to the LED chip with the90nmn-AlGaN EBL, the emission intensity of the LED chip with the100nm and110nmn-AlGaN layers are enhanced by5.4%and11.3%, respectively.2. With a p-type AlGaN electron-blocking layer inserted between the InGaN/GaNmultiquantum well (MQW) active region and the p-type GaN layer, the emissionproperties of GaN-based LEDs has been investigated. When the injection current is20mA, the emission intensity of green GaN-based LEDs with50nm p-AlGaN layer is326.46mcd. Compared to the LED chip with the50nm p-AlGaN EBL, the emissionintensity of the LED chip with the55nm and60nm p-AlGaN layers are decreased by3.93%and6.88%, respectively.These results show that, the optimized n-AlGaN electron-blocking layer and p-AlGaN electron blocking layer inserted in a green GaN-based LED structure cangreatly improve the green GaN-based LED luminous efficiency and light output power.Furthermore, the AlGaN electron-blocking layers are very promising for highefficiency and high-power GaN-based LED.
Keywords/Search Tags:GaN LED, Light output, Electron-blocking layer, AlGaN, MOCVD
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