Observation of resonant tunneling through InAs quantum dots by using novel electrophotoluminescence spectroscopy

The resonant tunneling through single InAs quantum dots embedded in an GaAs/i-Al_0.38Ga_0.62As/n-GaAs diode has been studied by using microscopic electrophotoluminescence spectroscopy. A group of sharp luminescence lines which originate from single quantum dots was observed by injecting resonant electrons from the emitter to the dots. Bias dependence of a single luminescence line has been investigated. The peak intensity shows triangular dependence which is similar to the current-voltage characteristics of 3D-0D resonant tunneling. When the bias voltage increases, the peak energy slightly shifts to a lower energy indicating the existence of stark effect, and the linewidth slightly increases. Moreover, the higher the luminescence energy is, the broader the linewidth is. This result agrees with the calculated resonant level width. The lifetime of resonant states is estimated to be 2.4-27 ps for luminescence linewidth of 250-22 μeV