An AlGaN/GaN HEMT with a reduced surface electric field and an improved breakdown voltage
An AlGaN/GaN HEMT with a reduced surface electric field and an improved breakdown voltage
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DOI：
10.1088/1674-1056/21/8/086105
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发表时间：
2012-08
影响因子：
1.7
通讯作者：
G. Xie 谢;B. Zhang 张;E. Xu;N. Hashemi;F. Y. Fu;W. Ng
中科院分区：
文献类型：
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作者：
G. Xie 谢;B. Zhang 张;E. Xu;N. Hashemi;F. Y. Fu;W. Ng
通过在二维电子气 (2-DEG) 通道下采用局域镁掺杂层作为电场整形层，研究了 AlGaN/GaN 高电子迁移率晶体管 (HEMT) 中表面电场的降低。与相同器件物理尺寸的传统源极连接场板和双场板结构的HEMT相比，栅极边缘周围的电场强度得到有效缓解，表面电场分布均匀。与具有传统源极连接场板和双场板的HEMT相比，具有Mg掺杂层的HEMT还表现出击穿位置从栅极边缘表面转移到体Mg掺杂层边缘。通过优化Mg掺杂层的长度Lm和掺杂浓度，与源极连接场板结构和双场板结构的HEMT相比，漏极侧栅极边缘附近的峰值电场分别降低了5.5倍和3倍。在 VGS = −5 V、Lm = 1.5 μm、峰值 Mg 掺杂浓度为 8×1017 cm−3、漂移区长度为 10 μm 的器件中，观察到击穿电压从没有场板结构的传统器件中的 560 V 增加到 900 V 以上，而没有任何面积开销损失。
A reduced surface electric field in an AlGaN/GaN high electron mobility transistor (HEMT) is investigated by employing a localized Mg-doped layer under the two-dimensional electron gas (2-DEG) channel as an electric field shaping layer. The electric field strength around the gate edge is effectively relieved and the surface electric field is distributed evenly as compared with those of HEMTs with conventional source-connected field plate and double field plate structures with the same device physical dimensions. Compared with the HEMTs with conventional source-connected field plates and double field plates, the HEMT with a Mg-doped layer also shows that the breakdown location shifts from the surface of the gate edge to the bulk Mg-doped layer edge. By optimizing both the length of Mg-doped layer, Lm, and the doping concentration, a 5.5 times and 3 times the reduction in the peak electric field near the drain side gate edge is observed as compared with those of the HEMTs with source-connected field plate structure and double field plate structure, respectively. In a device with VGS = −5 V, Lm = 1.5 μm, a peak Mg doping concentration of 8×1017 cm−3 and a drift region length of 10 μm, the breakdown voltage is observed to increase from 560 V in a conventional device without field plate structure to over 900 V without any area overhead penalty.