Bias induced strain in AlGaN/GaN heterojunction field effect transistors and its implications
Bias induced strain in AlGaN/GaN heterojunction field effect transistors and its implications
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DOI：
10.1063/1.2203739
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发表时间：
2006-05-15
影响因子：
4
通讯作者：
Smith, KV
中科院分区：
文献类型：
--
作者：
Anwar, AFM;Webster, RT;Smith, KV
我们报道了由压电极化引起的电荷与栅极偏置的关系，这是通过使用基于应力和电位移的压电本构方程的全耦合公式得到的。这一公式具有重要意义，因为它充分考虑了全局电荷控制约束下的机电耦合。对于给定的铝摩尔分数，与非耦合配方相比，耦合配方由于压电极化而产生更低的电荷。随着二维电子气浓度的增加，即栅偏压大于阈值时，势垒AlGaN层中沿c轴方向的压应变随着面内应力的增加而增加。电流崩塌与源极和漏极电阻的增加有关，因为它们依赖于表面电荷。本文还给出了电流崩塌的另一种解释：局部电荷中性。
We report gate bias dependence of the charge due to piezoelectric polarization obtained by using a fully coupled formulation based upon the piezoelectric constitutive equations for stress and electric displacement. This formulation is significant because it fully accounts for electromechanical coupling under the constraint of global charge control. The coupled formulation results in lower charge due to piezoelectric polarization as compared to the uncoupled formulation for a given Al mole fraction. With increasing two dimensional electron gas concentration, that is, for gate biases greater than threshold, the compressive strain along the c axis in the barrier AlGaN layer increases with a concomitant increase of in-plane stress. Current collapse is correlated to the increase in source and drain resistances through their dependence upon surface charge. An alternate explanation of current collapse using local charge neutrality is also presented.