The compounds exhibit piezoelectricity, which demands to break inversion symmetry, and then to be a semiconductor. For Ga2O3, the orthorhombic case (epsilon-Ga2O3) of common five phases breaks inversion symmetry. Here, the piezoelectric tensor of epsilon-Ga2O3 is reported by using density functional perturbation theory (DFPT). To confirm semiconducting property of epsilon-Ga2O3, its electronic structures are studied by using generalized gradient approximation (GGA) and Tran and Blaha's modified Becke and Johnson (mBJ) exchange potential. The gap value of 4.66 eV is predicted with mBJ method, along with the effective mass tensor for electron at the conduction band minimum (CBM) [about 0.24 m(0)]. The mBJ gap is very close to the available experimental value. The elastic tensor C-ij are calculated by using the finite difference method (FDM), and piezoelectric stress tensor e(ij) are attained by DFPT, and then piezoelectric strain tensor d(ij) are calculated from C-ij and e(ij). In this process, average mechanical properties of epsilon-Ga2O3 are estimated, such as bulk modulus, Shear modulus, Young's modulus and so on. The calculated d(ij) are comparable and even higher than commonly used piezoelectric materials such as alpha-quartz, ZnO, AlN and GaN.
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机译:该化合物表现出压电性,需要断裂反转对称性,然后是半导体。对于Ga2O3,常见五相的正交壳体(Epsilon-Ga 2 O 3)破坏反转对称性。这里,通过使用密度函数扰动理论(DFPT)报道EPSILON-GA2O3的压电张量。为了确认EPSILON-GA2O3的半导体性能,通过使用广义梯度近似(GGA)和TRAN和BLAHA的修改BECKE和JOHNSON(MBJ)交换潜力来研究其电子结构。使用MBJ方法预测4.66eV的间隙值,以及导通带最小(CBM)的电子的有效质量张量[约0.24m(0)]。 MBJ差距非常接近可用的实验值。通过使用有限差分方法(FDM)来计算弹性张量C-IJ,并且通过DFPT实现压电应力张量E(IJ),然后通过C-IJ和E计算压电应变张量D(IJ)(IJ )。在该过程中,估计EPSILON-GA2O3的平均机械性能,例如散装模量,剪切模量,杨氏模量等。计算的D(IJ)是相当的,甚至高于常用的压电材料,例如α-石英,ZnO,AlN和GaN。
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