Enhancement of SSI-LED Light Emission by Embedding CdS in the Zr-Doped HfO₂High-kFilm

Abstract

Light emission improvement of the solid state incandescent light emitting devices by embedding CdS into the Zr-doped HfO2 high-k dielectric has been studied. Compared with the capacitor with the Zr-doped HfO2 gate dielectric, the CdS embedded sample have: 1) higher defect densities in bulk and interface layers, 2) a smaller breakdown strength, 3) a larger leakage current, 4) more light emission dots, and 5) a higher light emission intensity. The spectrum shape and color of the emitted light were influenced by the inclusion of CdS in the high-k stack. The light emission efficiency was also enhanced. The improvement might be caused by the change of the nano-resistor composition. In summary, the embedding of CdS influences the high-k stack's physical properties, which affects the formation of nano-resistors and the device's light emission characteristics.

Simulation of Light Intensity and Nano-Resistor Distribution in SSI-LEDs Using Python as a Framework

“…Figure 4 shows (a) a photo of light emitting from NRs in a fabricated ZrHfO/CdS/ZrHfO high-k layer SSI-LED of gate diameter 300 μm at V g = −50 V, 20 and (b) a simulated figure of 5,500 NRs using the Python script described in the previous section. Below both images are greyscale versions for better comparison.…”

“…16,17 The NRs are formed from the dielectric breakdown of a metal oxide semiconductor (MOS) capacitor made on a Si wafer with a high-k dielectric, such as zirconium doped hafnium oxide (ZrHfO), and a transparent indium tin oxide (ITO) gate electrode. [17][18][19][20] When a large current passes through the NR, the local temperature becomes high enough to emit light according to the principle of black body radiation. The emitted light has a color corrected temperature (CCT) of 3,000-4,000 K and a color rendering index (CRI) greater than 95.…”

“…This is consistent with the experimental observation that the density of NRs in the former region is larger than that in the latter region. 20 COMSOL Multiphysics was used to simulate the steady state operation of an SSI-LED with a few NRs of fixed sizes. 23,24 The program uses the Finite Element Method to solve systems of differential equations for a control volume defined by the boundary conditions at the exterior surfaces of a 3D model.…”