RTD Light Emission around 1550 nm with IQE up to 6% at 300 K

Resonant tunneling diodes (RTDs) have come full-circle in the past 10 years after their demonstration in the early 1990s as the fastest room-temperature semiconductor oscillator, displaying experimental results up to 712 GHz and f max values exceeding 1.0 THz [1] . Now the RTD is once again the preeminent electronic oscillator above 1.0 THz and is being implemented as a coherent source [2] and a self-oscillating mixer [3] , amongst other applications. This paper concerns RTD electroluminescence - an effect that has been studied very little in the past 30+ years of RTD development, and not at room temperature. We present experiments and modeling of an n-type In 0 .53Ga 0 .47As/AlAs double-barrier RTD operating as a cross-gap light emitter at ~300K. The MBE-growth stack is shown in Fig. 1(a) . A 15-μm-diam-mesa device was defined by standard planar processing including a top annular ohmic contact with a 5-μm-diam pinhole in the center to couple out enough of the internal emission for accurate free-space power measurements [4] . The emission spectra have the behavior displayed in Fig. 1(b) , parameterized by bias voltage (V B ). The long wavelength emission edge is at λ = 1684 nm - close to the In 0.53 Ga 0 . 47 As bandgap energy of U g ≈ 0.75 eV at 300 K. The spectral peaks for V B = 2.8 and 3.0 V both occur around λ = 1550 nm (hv = 0.75 eV), so blue-shifted relative to the peak of the "ideal", bulk InGaAs emission spectrum shown in Fig. 1(b) [5] . These results are consistent with the model displayed in Fig. 1(c) , whereby the broad emission peak is attributed to the radiative recombination between electrons accumulated on the emitter side, and holes generated on the emitter side by interband tunneling with current density J interr . The blue-shifted main peak is attributed to the quantum-size effect on the emitter side, which creates a radiative recombination rate R N,2 comparable to the band-edge cross-gap rate R N,1 . Further support for this model is provided by the shorter wavelength and weaker emission peak shown in Fig. 1(b) around λ = 1148 nm. Our quantum mechanical calculations attribute this to radiative recombination R R,3 in the RTD quantum well between the electron ground-state level E 1,e , and the hole level E 1,h .