Geiger-mode operation of ultraviolet avalanche photodiodes grown on sapphire and free-standing GaN substrates
Geiger-mode operation of ultraviolet avalanche photodiodes grown on sapphire and free-standing GaN substrates
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DOI：
10.1063/1.3457783
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发表时间：
2010-07
影响因子：
4
通讯作者：
E. Cicek;Z. Vashaei;R. Mcclintock;C. Bayram;M. Razeghi
中科院分区：
文献类型：
--
作者：
E. Cicek;Z. Vashaei;R. Mcclintock;C. Bayram;M. Razeghi
GaN雪崩光电二极管（APD）生长在常规蓝宝石和低位错密度自支撑（FS）c面GaN衬底上。比较了这些APD的漏电流、增益和单光子探测效率。在70 V的反向偏压下，蓝宝石衬底上生长的APD显示出2.7×10−4 A/cm 2的暗电流密度，而FS-GaN衬底上生长的APD的暗电流密度明显较低，为2.1×10−6 A/cm 2。在线性工作模式下，生长在FS-GaN上的APD的雪崩增益高达14 000。研究了增强型SPDE的盖革模式操作条件。在正面照明下，当生长在蓝宝石衬底上时，625 μm2面积的APD产生约13%的SPDE，而当生长在FS-GaN上时，SPDE超过24%。蓝宝石衬底上的相同APD的SPDE在背照下增加到约30%-由于厚的吸收GaN衬底，FS-GaN APD仅在前照下测试。
GaN avalanche photodiodes (APDs) were grown on both conventional sapphire and low dislocation density free-standing (FS) c-plane GaN substrates. Leakage current, gain, and single photon detection efficiency (SPDE) of these APDs were compared. At a reverse-bias of 70 V, APDs grown on sapphire substrates exhibited a dark current density of 2.7×10−4 A/cm2 whereas APDs grown on FS-GaN substrates had a significantly lower dark current density of 2.1×10−6 A/cm2. Under linear-mode operation, APDs grown on FS-GaN achieved avalanche gain as high as 14 000. Geiger-mode operation conditions were studied for enhanced SPDE. Under front-illumination the 625-μm2-area APD yielded a SPDE of ∼13% when grown on sapphire substrates compared to more than 24% when grown on FS-GaN. The SPDE of the same APD on sapphire substrate increased to ∼30% under back-illumination—the FS-GaN APDs were only tested under front illumination due to the thick absorbing GaN substrate.