Lattice Temperature Model and Temperature Effects in Oxide-Confined VCSEL’s

Abstract

A lattice temperature model is derived for oxide-confined vertical cavity surface emitting lasers (VCSELs) based on carrier transport and the conservation of energy. Peltier heat is caused by the bandedge and quasi-Fermi level discontinuities at a heterojunction. However, considering the device size, Peltier heat needs to be distributed and is not just generated at the interface, otherwise, an anomolous spike in temperature will occur. We have developed a novel treatment to model the Peltier heat at a heterojunction by use of a Monte Carlo simulation. Peltier heat is found to be a major heat contributor, and it results in a rapid and high temperature rise in the separate confinement heterostructure (SCH) region of the laser diode. We have also shown that the carrier thermal conductivities for materials with high mobilities must be included at high carrier densities because they contribute to additional spreading of the thermal energy. Subsequently, this lattice temperature model is coupled self-consistently to electronic and optical solvers to form a complete simulator for VCSELs. Self-heating causes a fast temperature rise when the VCSEL is operated under continuous wave conditions, causing resonant wavelength changes and an eventual thermal rollover. The resonant wavelength shift has been shown to be caused mainly by the heating of the distributed Bragg reflectors even though the peak temperature occurs within the SCH region. Possible physical factors causing the thermal rollover have also been examined with our complete simulator. The Auger recombination process is found to be one of the main factors causing the thermal rollover in 980 nm oxide-confined VCSELs while the photon lifetime is a factor in determining the position of the thermal rollover. We have also achieved a very good match between our simulated results and experimental data.

Impact of thermoelectric phenomena on phase-change memory performance metrics and scaling

“…at the junction of two materials with the Seebeck coefficient difference S. At the interface, the charge carriers lose energy to the lattice by scattering over a few mean free paths, and the energy distribution can be precisely calculated by Monte Carlo simulations [14]. Peltier heating may spread over a distance due to local Seebeck coefficient variations or non-equilibrium carrier concentrations near the junction [15,16].…”

Self-Heating Analysis of 1570 nm InGaAsP Buried Tunnel Junction Photonic Crystal VCSEL

“…It should be mainly due to expansion of the gain spectrum and the overflow of carriers in the hetero--barriers. On the other hand, the leakage currents or dark recombination processes are temperature--dependent that they cause the thermal rollover effect in the characteristics of BTJ--PhC VCSEL (Ng et al, 2004).…”