Simulation of Gallium Nitride/Aluminum Nitride-Based Triple Barrier Quantum Region for ULTRARAM Application

Abstract

ULTRARAM is a low-power, high-speed, nonvolatile compound semiconductor memory device that uses triple barrier resonance tunneling (TBRT) to store electrical charge in a floating gate. Using a self-consistent solution of Schrödinger-Poisson equations, we investigated the electrical properties, transmission spectra, and electron dynamics across GaN/AlN TBRT region for the ULTRARAM application. The simulation results show that GaN/AlN exhibits tunable electrical properties by using a TBRT region of variable thickness. Successive optimization and testing of various thicknesses significantly altered the transmission across multiple barriers and localization of electrons in the quantum wells. The program/erase (P/E) operation of GaN/AlN-based ULTRARAM in a triple barrier structure is accomplished at less than 2 V. The device’s excellent nonvolatility is due to the conduction band offset (CBO) of GaN/AlN heterostructure providing a large energy barrier (2.1 eV), which prevents electrons from escaping from the floating gate. Because of the low voltage operation and small capacitance, the switching energy consumption is much lower than that of a standard floating gate Flash.