Radiative recombination of two-dimensional electrons in a modulation-doped Al0.37Ga0.63N/GaN single heterostructure

We have studied the low-temperature (4 K) photoluminescence (PL) of a modulation-doped Al0.37Ga0.63N/GaN single heterostructure. Radiative recombination is observed between electrons in the two-dimensional quantum states at the heterointerface and holes in either the flatband region or bound to residual acceptors. This PL emission disappears when the top AlGaN layer is removed by reactive ion etching, indicating that the luminescence is from the two-dimensional electron states. From the peak separation of the luminescence related to the two-dimensional electrons, the maximum electric field at the heterointerface is estimated to be 3.7×104 V/cm.