摘要:

We have observed a far‐infrared (0.3–2.5 THz) radiation‐induced photovoltaic signal in an antenna‐coupled quantum point contract, which oscillates with the gate voltage and peaks at the onset of each subband. The polarity of this photovoltaic signal can be reversed by shifting the far‐infrared beam from the drain to the source, or vice versa. This signal has been unambiguously attributed to thermopower generated by asymmetric heating of the drain and the source by the far‐infrared radiation. Quantitative agreement has been obtained between measurements and calculations based on ballistic transport in one‐dimensional electron systems and the electrical and thermal circuit elements in our experimental system. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113840

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The variation of electric field gradient above arrays of field emission cathodes has been investigated using atomic force microscopy. The spatial distribution of electric field gradient was obtained as a function of bias and height. Results show a parabolic relationship between the sample bias and electric field gradient. Furthermore, the height dependence of the field gradient is found to follow a power law relationship. These new results demonstrate that force‐gradient atomic force microscopy is capable of providing a direct visual presentation of the variation of field gradients above submicron‐periodicity field emitter arrays. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113841

出版商:AIP    

年代:1995

数据来源: AIP