Modulation of Schottky barrier at metal/Ge contacts by phosphoric acid coating and excimer laser annealing
Modulation of Schottky barrier at metal/Ge contacts by phosphoric acid coating and excimer laser annealing
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DOI：
10.1016/j.mssp.2023.107433
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发表时间：
2023-06
影响因子：
4.1
通讯作者：
K. Katayama;H. Ikenoue;T. Sadoh
中科院分区：
文献类型：
--
作者：
K. Katayama;H. Ikenoue;T. Sadoh
锗是一种用于先进器件如高速晶体管和高效光学器件的有吸引力的材料。为了实现高性能的操作，需要低电阻接触到Ge。然而，在金属/Ge接触处的Ge中的费米能级经常被钉扎在价带边缘附近。无论金属的功函数如何，这种费米能级钉扎在金属/Ge接触处产生高肖特基势垒高度，这导致与p型Ge的低电阻接触，但与n型Ge的高电阻接触。因此，需要一种用于调制金属/Ge接触处的肖特基势垒高度的技术。为此目的，使用磷酸涂层和准分子激光退火（LA）的Ge表面处理的效果进行了研究。在无磷酸涂层的LA之后，Al/n型Ge接触的反向电流增加了一个数量级。另一方面，反向电流显着增加了三个数量级后，LA与磷酸涂层。在这里，肖特基势垒高度分别从0.56至0.50 eV和从0.59至0.49 eV后LA的样品没有和磷酸涂层，分别。这些现象归因于形成非常薄的GeOx表面层和非常浅的掺杂层具有非常高的P浓度，分别。这种技术是有用的调制费米能级钉扎的金属/锗接触与低热预算。
Germanium is an attractive material for advanced devices such as high speed transistors and high efficiency optical devices. To realize the high performance operation, low resistive contacts to Ge are required. However, the Fermi level in Ge at metal/Ge contacts is often pinned near the valance band edge. This Fermi level pinning generates high Schottky barrier heights at metal/Ge contacts regardless the work function of the metals, which results in low resistive contacts to p-type Ge but high resistive contacts to n-type Ge. Thus, a technique for modulating the Schottky barrier heights at metal/Ge contacts is desired. For this purpose, effects of surface treatments of Ge using phosphoric acid coating and excimer laser annealing (LA) were investigated. After LA without phosphoric acid coating, the reverse current of the Al/n-type Ge contacts is increased by an order of magnitude. On the other hand, the reverse current is significantly increased by three orders of magnitude after LA with phosphoric acid coating. Here, the Schottky barrier heights are decreased from 0.56 to 0.50 eV and from 0.59 to 0.49 eV after LA for samples without and with phosphoric acid coating, respectively. These phenomena are attributed to formation of very thin GeOxsurface layers and very shallow doped layers having very high P concentrations, respectively. This technique is useful for modulation of the Fermi level pinning for metal/Ge contacts with the low thermal budget.