Quiz12_solutions_spring2010

Quiz12_solutions_spring2010 - Quiz 12 ChE 350 Spring 2010 =...

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Unformatted text preview: Quiz 12; ChE 350 Spring 2010 = . . Name:_%— 1. An LED with the architecture shown below on the left emits light with the spectrum shown on the right. ‘ The light emitting layer is composed of InxGa1-xN. [From K. Murakami, et al. “White illumination characteristics of ZnS-based phosphor materials excited by InGaN—based ultraviolet light-emitting diode,” Preceedz'ngs of SPIE Vol. 4079 (2000) 112-119.]. The band gap energies of AlN, GaN and lnN are 6.2 eV, 3.4 eV and 0.8 eV, respectively. p—electrode \ p—GaNzMg 0.15 um .4 g p-Alo.2Gao.s N E barrier layer —— g. InxGaxar'N 'SOA “" 3 “ n-electrode g n-Alo.2Gao.sN ”— E barrier layer E Ilf-GENZSl 5 pm ~— g GaN buffer 300A - ""7 ‘" sapphire 3.: 3.2 3:3 ‘ 34 3.5 substrate moron may {eVl 3;? ~ ’é. 2 § cV Fig.1 A schematically drawing of the cross section of lnGaNlAlGaN Fig.2 (a) Emission spectra obtained at RT SQW UV LED having attractive layer of ,InxGa._xN (xi-70). I between 2.9 and 4.1 V. \ (A) Based on the emission spectra above, What is the composition of the In xGa1_ N layer (show your work)? J4me 33:53; 3 33W law we 39% t ,X) % 331v \ X21060 32,. ‘ :‘A 902‘ C70\ afli g M (B) Sketch the band diagram for the p- A10_2Gao_8N/ .InxGa1_ N/n-AlogGaogN heterojunction. Alwagug Mm) + Mm) 1.7724 4-— 7,.7; .3 3/“? eV’ P H 3.1% 5:75: Wane _~, ' ' \/ (C) On your band diagram, draw arrows showing the direction of electron and hole flow when the LED is producing light. P, amalgam} ...
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