Spontaneous-light emitting devices based on microcavity-induced spontaneous emission control

在本课题中，我们研究了利用半导体微腔的自发发光器件，该器件具有高效率的定向辐射和非常高速的开关能力。特别是针对实际应用，重点研究了该器件在室温下工作的实现。在第一年（1988年），我们详细研究了已经制作好的微腔发光三极管在低温下的操作。该装置既具有注入电流的功能，又具有对量子阱施加静电的功能。在恒流注入下，我们证实了发射波长随施加于量子阱电压的变化而连续变化，发射强度随波长变化而变化。当发射波长调谐到腔共振时，强度达到峰值。此外，随着发射波长的增加，辐射模式也发生了变化。根据这些结果，我们得出结论，在发射波长和施加在器件上的电压的控制下，微腔的存在改变了自发发射。然而，该装置的辐射模式是不对称的。通过实验，我们推测不对称辐射的原因与p-n结偏置的导电层之间的电阻差异导致的局部载流子注入有关。第二年（1999年），我们重新设计了这个装置。我们在室温下对新器件进行了表征，发现其辐射模式是对称的。此外，在电流注入载流子的情况下，通过改变器件上的偏置电压，确定了器件的基本功能，即随着发射波长的变化，器件的辐射方向图和辐射强度会发生变化。因此，我们可以得出结论，基于半导体微腔的自发光发射器在室温下工作良好。然而，不幸的是，外部量子效率非常低，很可能是由于晶体质量差。因此，为了使这些器件在实际应用中得到应用，未来有必要实现更高质量的材料。少

In this project, we studied the spontaneous-light emitting devices, which exhibit the directional radiation with high efficiency and has a capability of very high speed switching, using semiconductor microcavities. Particularly, aiming at the practical application, we focused on the realization of such devices working at room temperature.In the first year (1988), we studied the operation at low temperature in detail in the microcavity light-emitting triode which had been already fabricated. The device has both the functions of current injection and the application of static electric field to the quantum well. Under the constant current injection, we confirmed the continuous change of emission wavelength with the change of the voltage applied to the quantum well, and the change of emission intensity associated with the wavelength-change. The intensity was peaked when the emission wavelength is tuned to the cavity resonance. In addition, the radiation patterns were varied with the change … More of the emission wavelength. From these results, we concluded that the spontaneous emissions were altered by the presence of the microcavity under the control of emission wavelength by the voltage applied to the device. However, the radiation pattern in the device was asymmetric. Through the experiment, we speculated that the reason of the asymmetric radiation is related the local carrier injection due to the difference of resistance between the conducting layers thorough which the p-n junction is biased.In the second year (1999), we re-designed the device. We characterized the new devices at room temperature, and found that the radiation patterns were symmetric. In addition, we confirmed the basic functions of the device, namely the change of radiation pattern and intensity with the change of emission wavelength by the change of the bias voltage applied to the devices, under the injection of carriers by current. Hence, we can conclude that the spontaneous light emitters based on semiconductor microcavities were confirmed to work well at room temperature. Unfortunately, however, the external quantum efficiency was very low, most likely to be due to the poor crystalline quality. Therefore, to apply the devices in practical use, it is necessary to realize higher quality materials in future. Less