Carrier Escape and the Ideality Factor in Quantum Dot p-n Junctions

The ideal diode approximation is used to evaluate the properties of many semiconductor diode-based devices. However, when it is applied to lasers and photovoltaics, which incorporate quantum dots (QDs), the ideality factors measured are difficult to interpret. Here, we show that a proper consideration of carrier escape from the QD confined states overcomes this problem. In addition, this approach suggests a novel method of empirically estimating the absolute value of the escape current at the threshold current of a laser diode. We argue that this technique will be of great importance in the experimental analysis of nonradiative losses in lasers and should also prove useful to the development of next-generation QD photovoltaics where thermal carrier escape must be minimized.