[20p-C401-1~16] 13.6 Nanostructures, quantum phenomena, and nano quantum devices

▲ [20p-C401-7] Electron temperature in semiconductor double barrier thermionic cooling heterostructures

〇Xiangyu Zhu¹, Marc Bescond², Gerald Bastard³, Naomi Nagai¹, Kazuhiko Hirakawa^1,2 (1.IIS/INQIE,Univ. of Tokyo, 2.LIMMS-CNRS, 3.Ecole Normale Superieure)

Keywords:semiconductor, heterostructure, thermionic cooling

Managing rapid increase in thermal power densities associated with device miniaturization is a major technological challenge. Development of new efficient cooling technologies is therefore urgently required for future progress in electronics. Solid-state cooling devices can be one answer, owing to their high efficiency and compatibility for integration. To achieve efficient cooling, we have been working on semiconductor double barrier heterostructures to utilize the thermionic cooling effect. In the present heterostructure, cold electrons are first injected into the quantum well (QW) by resonant tunneling through the thin barrier (emitter barrier). Subsequently, hot electrons are removed by thermionic emission over the second thick barrier (collector barrier). This sequential two-step conduction process is essential for the cooling effect. To quantitatively understand the conduction process, we have developed an analytical theory to calculate the two-step current and compared it with experiment. In this work, we have considered not only the current flow but also the energy balance in the electron system in the QW. The electron temperature in the QW can be calculated and compared with experimental data.
Based on the electron temperature calculation, we start to investigate the structure-dependence of electron cooling. The height (determined by Al component) and thickness of energy barrier is modified. Also, the quantized state position is varied by changing the width of QW. We find the energy difference W between the collector barrier height Vb and the quantized state E1 is the main factor that determines the magnitude of electron cooling. The relationship shows that the maximum electron cooling takes place when W=kbT. Meanwhile, systematic experiments on the effect of W are in progress. More details will be discussed at the meeting.