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arXiv 1209.5528cond-mat.mtrl-scicond-mat.mes-hall
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强磁场对Pb-p-HgCdTe肖特基势垒上输运的影响

Strong magnetic field effect on above-barrier transport in Pb-p-HgCdTe Schottky barriers

V. F. Radantsev, V. V. Zavyalov

摘要:

由于轻重空穴的有效质量相差很大,通常认为p型半导体肖特基势垒中的势垒上电流只由重空穴控制。然而,在实际结构中,存在由界面处的氧化物层引起的额外势垒。对于典型的势垒厚度和高度值,轻空穴的隧穿透明性比重空穴的隧穿透明性高三个数量级。由于绝缘层的这种分离作用,可以预期电流主要是光空穴的贡献。为了解决这一问题,我们将磁场中输运的研究作为本工作的一个关键实验。在二极管和扩散输运机制的框架内,只有在极强的磁场B>10 T时,才能在研究的Pb-p-HgCdTe肖特基势垒中对重空穴产生显著的磁场效应。同时,在实验上观察到超过两倍的饱和电流减少,即使在B=0.5 T在任何方向的磁场。对不同Kane带隙和不同温度下HgCdTe的研究表明,磁场效应的大小唯一地取决于轻空穴回旋能量与热能的比值。然而,影响的幅度大大超过了简单理论的预测,并且饱和电流的实验磁场依赖性不遵循对超声波电流预测的简单指数下降。这种差异的原因仍然是一个谜。

英文摘要:

Due to large difference in effective masses of light and heavy holes it is usually supposed that the above-barrier current in Schottky barriers on p-type semiconductor is controlled only by the heavy holes. However, in real structures, there is an additional potential barrier caused by a oxide layer at interface. For typical values of thickness and height of a barrier its tunnel transparency for light holes can be higher by three order of magnitude than that for heavy holes. Due to such separative role of insulator layer one can expect that the current is manly a contribution of light holes. To clear up this problem the investigation of transport in a magnetic field is used as a key experiment in this work. The pronounced magnetic field effect for heavy holes in investigated Pb-p-HgCdTe Schottky barriers is expected only at extremely strong magnetic fields B>10 T within the framework of both diode and diffusion mechanism of transport. At the same time experimentally more than twofold decrease in saturation current is observed even at B=0.5 T at any orientation of magnetic field. The studies performed for HgCdTe with different Kane's gap and at different temperatures show that the magnitude of magnetic field effect is uniquely determined by the ratio of light hole cyclotron energy to a thermal energy. However the magnitude of effect exceeds considerably the prediction of the simple theory and the experimental magnetic field dependencies of a saturation current do not follow the simple exponential falling predicted for thermionic current. The reason of this discrepancy remains a mystery.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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