We report new capabilities in our Sentaurus-Device<sup>1</sup> simulator for modeling arbitrarily shaped 2D/3D white
LEDs by coupling novel photon recycling, luminescent spectral conversion effects and electrical transport self
consistently. In our simulator, the spontaneous emission spectra are embedded in ray tracing, and are allowed
to evolve as the rays traverse regions of stimulated gain, absorption, and luminescence. In the active quantum
well (QW), the spontaneous emission spectrum can be partially amplified by stimulated gain within a certain
energy range and absorbed at higher energies, resulting in a modified spontaneous spectrum. The amplified
and absorbed parts of the spectrum give a net recombination/generation rate that is feedback to the electrical
transport via the continuity equations. This conceives a novel photon recycling model that includes amplified
spontaneous emission. The modified spontaneous spectrum can further be altered by spectral conversion in the
luminescent region. In this manner, we capture the important physical effects in white LED structures in a fully
coupled and self-consistent electro-opto-thermal simulation.
This paper illustrates how technology computer-aided design (TCAD), which nowadays is an essential part of CMOS
technology, can be applied to LED development and manufacturing. In the first part, the essential electrical and optical
models inherent to LED modeling are reviewed. The second part of the work describes a methodology to improve the
efficiency of the simulation procedure by using the concept of process compact models (PCMs). The last part
demonstrates the capabilities of PCMs using an example of a blue InGaN LED. In particular, a parameter screening is
performed to find the most important parameters, an optimization task incorporating the robustness of the design is
carried out, and finally the impact of manufacturing tolerances on yield is investigated. It is indicated how the concept
of PCMs can contribute to an efficient design for manufacturing DFM-aware development.
This paper first gives an overview of state-of-the-art simulation of semiconductor laser devices. The relevant physical models for multi dimensional, electro thermal, and optical simulation as well as an advanced active region model are reviewed. The second part of this work deals with the management of laser simulation projects and the extraction of the relevant data from simulation results. A new tool called PCM Explorer is presented that is suitable for the integration of numerical models in the design and manufacturing process of semiconductor lasers. Both the device performance as well as the process yield can be predicted with the combination of a comprehensive device simulator, some measurement data for calibration purposes, and the statistical process evaluation tool.
We propose a novel treatment that enhances the accuracy of the Effective Index Method (EIM) when used for gain-guided oxide-confined VCSELs. If a thin oxide is placed at or near a z-field null position, the diffraction caused by the oxide becomes negligible. Gain-guiding subsequently dominates and causes the EIM to break down. To circumvent this problem, we propose to use an artificial index-guided diffraction effect to simulate the gain-guided diffraction effect. This is achieved by increasing the oxide thickness and making a correction to the oxide index by taking a weighted sum between the original oxide index and the center region index at the oxide layer position. The weight is specifically chosen to be the mean z-field (normalized to its local z-field variation) at the position of the oxide. We show that this simple correction to the EIM successfully simulates the gain-guided diffraction effect and produces the correct transverse phase variation for oxide-apertured VCSELs when gain-guiding becomes the dominant mechanism. Therefore, the improved EIM is able to produce resonant wavelengths which are in excellent agreement to those of the vector Green's function method for the COST-268 VCSEL model, both in the gain-guided and index-guided regimes. Comparisons with an experimental model have also been made and excellent agreement is shown.
This work focuses on the effects of spatial hole-burning (SHB) on the modulation response of oxide-confined vertical-cavity surface-emitting lasers. The comprehensive laser diode simulator, Minilase, as well as a simple 1-D rate equation models are used as simulation tools in the studies. We demonstrate that, due to the non-uniform transverse optical intensity, carriers at different locations of the quantum well (QW) have different stimulated recombination rates, and therefore exhibit different dynamic responses under direct modulation. This non-uniformity is revealed to be responsible for an over-damping of the relaxation oscillation and the reduction of the modulation bandwidth. Due to the limit of this nonlinear effect, VCSELs with small oxide apertures show lower intrinsic maximum bandwidth compared with that of large aperture structures. Further simulations demonstrate that this damping effect can be greatly reduced by making the electrical aperture smaller than the optical aperture, thereby significantly improving the modulation response.