Simulation of Nano-resistor Patterns and the Effect of Embedded Tungsten on the Properties of the Solid State Incandescent Light Emitting Device

Abstract

The Solid-State Incandescent LED is an emergent optoelectronic device made on a Silicon wafer using IC-compatible materials and processes. Incandescence takes place by the Joule heating of numerous nano-scale, high resistivity conduction paths called nano-resistors, leading to warm white light emission from nano-resistors. Previously, finite element analysis was done using COMSOL Multiphysics to simulate the steady state operation of the device, while the light intensity distribution was separately simulated using MATLAB. These studies were restricted by the number of nano-resistors that could be generated, their size variations, and their distribution. A new Python framework is developed to simulate light emission and perform COMSOL simulations for any nano-resistor arrangement. The framework circumvents the nano-resistor count and distribution limitations of previous studies. These improvements allow for more sophisticated simulations of many more nano-resistors than previously possible, and investigation into the effect of nano-resistor count on the device. An alternative method was used to theoretically estimate nano-resistor thermal conductivity and rectify the unrealistic prediction of nano-resistor temperature of previous studies. Light emission of the device can be enhanced by using materials more suited to incandescence. The effect of tungsten on the emissive properties of the device was explored by comparing the spectral irradiance of samples made from ultrathin layers of tungsten embedded in zirconium doped hafnium oxide gate dielectrics in single layer and tri-layer structures. Through linear regression fitting of this data to Planck’s law alongside C-V and j-V measurements, the relative emissivity of nano-resistors, the radiant power, the total nano-resistor area as well the color corrected temperature was calculated. Embedded tungsten was shown to greatly increase emissivity of nano-resistors, however, a larger leakage current and charge trapping in the gate dielectric was observed, as well as fewer nano-resistors formed due to incompatibility of tungsten and zirconium doped hafnium oxide. Unless the incompatibility of tungsten with dielectric materials is resolved, tungsten is not suitable for the improving light emission of the device.