930 Ka/CM\u3csup\u3e2\u3c/sup\u3e Peak Tunneling Current Density in GaN/Aln Resonant Tunneling Diodes Grown on MOCVD GaN-On-Sapphire Template

We report on the design and fabrication of ultrahigh current density GaN/AlN double barrier resonant tunneling diodes grown via rf-plasma assisted molecular-beam epitaxy. The device structure was grown on a metal-organic chemical vapor deposition GaN-on-sapphire template. The devices displayed repeatable room temperature negative differential resistance with peak tunneling current densities (Jp) between 637 and 930 kA/cm2. Analysis of temperature dependent measurements revealed the presence of severe self-heating effects, which allow strong phonon scattering that deteriorates the electron quantum transport. Finally, a qualitative comparison to the same structure grown on a low dislocation density freestanding GaN substrate has shown that sapphire-based templates are a feasible alternative

Superior Growth, Yield, Repeatability, and Switching Performance in Gan-Based Resonant Tunneling Diodes

We report the direct measurement of record fast switching speeds in GaN/AlN resonant tunneling diodes (RTDs). The devices, grown by plasma-assisted molecular-beam epitaxy, displayed three repeatable negative differential resistance (NDR) regions below a bias of +6 V. A room temperature peak-to-valley current ratio (PVCR) \u3e 2 was observed, which represents a marked improvement over recent reports. Measurements carried out on hundreds of devices, of varying sizes, revealed a yield of ∼90%. Repeatability measurements consisting of 3000 sweeps resulted in a standard deviation, relative to the mean, of \u3c 0.1%. Temperature dependent measurements combined with non-equilibrium Green\u27s function based quantum transport simulations suggest the presence of both three-dimensional (3D) and two-dimensional (2D) emitters, giving rise to three NDR regions. Finally, a valley current density vs perimeter-to-area-ratio study indicates the presence of a surface leakage current mechanism, which reduces the PVCR

Effects of growth temperature on electrical properties of GaN/AlN based resonant tunneling diodes with peak current density up to 1.01 MA/cm2

Identical GaN/AlN resonant tunneling diode structures were grown on free-standing bulk GaN at substrate temperatures of 760 °C, 810 °C, 860 °C, and 900 °C via plasma-assisted molecular beam epitaxy. Each sample displayed negative differential resistance (NDR) at room temperature. The figures-of-merit quantified were peak-to-valley current ratio (PVCR), yield of the device with room-temperature NDR, and peak current density (Jp). The figures-of-merit demonstrate an inverse relationship between PVCR/yield and Jp over this growth temperature series. X-ray diffraction and transmission electron microscopy were used to determine the growth rates, and layer thicknesses were used to explain the varying figures-of-merit. Due to the high yield of devices grown at 760 °C and 810 °C, the PVCR, peak voltage (Vp), and Jp were plotted vs device area, which demonstrated high uniformity and application tunability. Peak current densities of up to 1.01 MA/cm2 were observed for the sample grown at 900 °C.publishedVersionPeer reviewe