High-electron-mobility (370 cm2/Vs) polycrystalline Ge on an insulator formed by As-doped solid-phase crystallization
High-electron-mobility (370 cm2/Vs) polycrystalline Ge on an insulator formed by As-doped solid-phase crystallization
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DOI：
10.1038/s41598-019-53084-7
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发表时间：
2019-11-12
影响因子：
4.6
通讯作者：
Toko, K.
中科院分区：
文献类型：
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作者：
Saito, M.;Moto, K.;Toko, K.
高电子迁移率的多晶Ge（poly-Ge）薄膜由于其结晶性差、缺陷诱导受主和n型掺杂剂的低固溶度而难以形成。在这里，我们发现，作为掺杂到非晶锗显着影响随后的固相晶化。虽然过量的As掺杂降低了多晶Ge的结晶度，但是适当量的As（类似于10（20）cm（-3））促进了横向生长，并且在375 ℃的生长温度下将Ge晶粒尺寸增加到约20 μ m。此外，中性的As原子在多晶Ge降低了陷阱态密度和晶界的能垒高度。这些性质减少了晶界散射，并允许在500 ℃退火后，在5 × 10（18）cm（-3）的电子浓度下，电子迁移率为370 cm（2）/Vs。电子迁移率进一步超过任何其它n型多晶Ge层，甚至超过n >= 10（18）cm（-3）的单晶Si晶片。绝缘体上高迁移率Ge的低温合成将为高性能Ge-CMOS到Si-LSI和平板显示器上的单片集成提供一条途径。
High-electron-mobility polycrystalline Ge (poly-Ge) thin films are difficult to form because of their poor crystallinity, defect-induced acceptors and low solid solubility of n-type dopants. Here, we found that As doping into amorphous Ge significantly influenced the subsequent solid-phase crystallization. Although excessive As doping degraded the crystallinity of the poly-Ge, the appropriate amount of As (similar to 10(20) cm(-3)) promoted lateral growth and increased the Ge grain size to approximately 20 [Jim at a growth temperature of 375 degrees C. Moreover, neutral As atoms in poly-Ge reduced the trap-state density and energy barrier height of the grain boundaries. These properties reduced grain boundary scattering and allowed for an electron mobility of 370 cm(2)/Vs at an electron concentration of 5 x 10(18) cm(-3) after post annealing at 500 degrees C. The electron mobility further exceeds that of any other n-type poly-Ge layers and even that of single-crystal Si wafers with n >= 10(18) cm(-3). The low-temperature synthesis of high-mobility Ge on insulators will provide a pathway for the monolithic integration of high-performance Ge-CMOS onto Si-LSIs and flat-panel displays.