Thermoreflectance spectroscopy—Analysis of thermal processes in semiconductor lasers

Abstract

This review focuses on theoretical foundations, experimental implementation and an overview of experimental results of the thermoreflectance spectroscopy as a powerful technique for temperature monitoring and analysis of thermal processes in semiconductor lasers. This is an optical, non-contact, high spatial resolution technique providing high temperature resolution and mapping capabilities. Thermoreflectance is a thermometric technique based on measuring of relative change of reflectivity of the surface of laser facet, which provides thermal images useful in hot spot detection and reliability studies. In this paper, principles and experimental implementation of the technique as a thermography tool is discussed. Some exemplary applications of TR to various types of lasers are presented, proving that thermoreflectance technique provides new insight into heat management problems in semiconductor lasers and in particular, that it allows studying thermal degradation processes occurring at laser facets. Additionally, thermal processes and basic mechanisms of degradation of the semiconductor laser are discussed.

Temperature dependence of secondary electron emission: A new route to nanoscale temperature measurement using scanning electron microscopy

“…Although this uncertainty is larger than one would like, it should still be relevant for applications like thermal hotspot mapping for device testing and failure analysis, which have temperatures typically reaching 100s of°C above the surrounding ambient. 21,22 It is noteworthy that even though β Grayscale is around 5× larger than the other three β's, the uncertainty δI=I ½ Grayscale is also similarly larger so that the final result for δT Grayscale remains consistent with the other three estimates. It must also be noted that the absolute temperature uncertainty for a new, uncalibrated sample is much larger than this detection limit, because of the background drifts and sample-to-sample variability in the I(T) response.…”

Developments on Thermometric Techniques in Probing Micro- and Nano-heat

“…With micro-Raman method, temperature resolution of ~5-10 K are given with spatial resolution depending on the excitation laser spot size 36 and can be below 1 μm, which is similar to thermoreflectance thermometry (section 3) but is improved considerably compared to the previous passive infrared thermometry with much longer wavelength (section 2). be observed with this technique.…”

“…4(a) and (b)) examines the inelastic scattering processes in a crystal, in which the incident photons are scattered by phonons leading to a shift in energies of the out scattered photons with creating or annihilating an optical phonon. The probability of the inelastic scattering is temperature-dependent and is related to the 36,42 occupation number of optical phonons. Measurement of the crystal lattice temperature is hence given often by the intensity ratio of the Stokes (S) and anti-Stokes (AS) lines or sometimes by their spectral [43][44][45][46] shift relative to the incident excitation light.…”

Facet Cooling in High-Power InGaAs/AlGaAs Lasers

“…The temperature modulated back-reflected light is collected with CMOS camera triggered by a diode driver and analyzed by a computer. The relation between the relative change in reflectivity and the temperature change is given as [10], [14], [20].…”