Vertical-conducting InGaN/GaN multiple quantum wells LEDs with AlN/GaN distributed Bragg reflectors on Si(111) substrate
In this study, crack-free InGaN/GaN multiple quantum well (MQW) LEDs with five-pair AlN/GaN distributed Bragg reflectors (DBRs) were grown on a Si(111) substrate using a linear compositionally graded AlGaN layer to compensate for tensile stresses. DBR-based LEDs exhibited higher light efficiency and better crystalline quality than non-DBR-based LEDs. Vertical-conducting DBR-based LEDs were realized using through-hole structure. Through-holes were formed from the n-GaN layer to the Si substrate and filled with metals, which connected the n-GaN layer and the Si substrate. Insulating AlN, high-resistivity AlGaN layers, and the large band offset at the AlN/Si interface were all shorted by the metal filled into the through-holes. Compared to DBR-based LED without through-holes, DBR-based LEDs with through-holes exhibited significantly better electrical and optical properties.
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