子带重叠对兆兆赫场驱动下的电阻分流半导体超晶格中直流偏置电压产生的影响

研究了处于外加高频交变场下的半导体超晶格中两个重叠子带内的弹道电子的运动。我们应用半经典的平衡方程途径来决定自发产生的直流电压和电流对于外加场的频率的依赖关系。数值模拟结果显示，在该频率范围的中段，直流电流的绝对值的包络线近似地随频率线性地衰减，然而在较高的外加交变场的频率下，如果在两个子带的电子平衡能量和电子占据几率之差达到一定的数值，自发的直流偏置电流的绝对值成为常数，而与外加交变场的频率无关。本文讨论了这一常数偏置电流和两个子带结构之间的关系，这对研究这种材料在超高频信息处理中的应用有一定意义。

Effect of miniband overlapping on generation of dc bias in a resistively shunted semiconductor superlattices driven by a tera hertz field

We consider the motion of ballistic electrons in two overlapped minibands of a semiconductor superlattic expose to an external high-frequency ac field. We use a semiclassical balance-equation appoach in determining the ac-frequency dependence of the dc voltage and current which are generated spontaneously. Our simulation reveals that the envelope of absolute values of the dc current is approximately a linearly decay function of the frequency in an intermediate range, but in the regime of higher ac frequencies there appears a constant absolute value of dc bias independent of the frequency if the differences in electron equilibrium energy and in electron occupation probability between two minibands exceed specific values. The relationship between this constant bias and the two miniband structure is discussed.