Photothermal rate-window spectrometry for noncontact bulk lifetime measurements in semiconductors

Abstract

A new noncontact technique for the determination of excess carrier lifetimes in semiconductors is presented. The technique employs a square laser pulse (hv > Eg) and measures the infrared photothermal radiometric response of the sample. By applying the photothermal rate-window concept, the excess photoexcited carrier bulk lifetime was measured with optimal signal-to-noise (S/N) ratio and simple, unambiguous interpretation from the maximum position of the rate-window signal. The technique has been applied to Au-, Fe-, and Cr-doped Czochralski silicon crystals. The experimental results from boxcar and lock-in rate-window methods were found to agree very well. The results are further mostly in agreement with those from the noncontact laser/microwave detection method.

Relative sensitivity of photomodulated reflectance and photothermal infrared radiometry to thermal and carrier plasma waves in semiconductors

“…[10][11][12][13][14][15] It has been shown earlier 14,15 that using a classical model for wave propagation in a free plasma 17 and assuming a depthindependent IR absorption coefficient of a semiconductor ␣ IR () (m Ϫ1 ), the linear PTR signal in a one-dimensional model is…”

“…9 Another recently established noncontact photothermal technique which has a number of potential advantages over PMR and other existing methodologies in characterization of both the thermal and electronic properties of semiconductors, is photothermal infrared radiometry ͑PTR͒. [10][11][12][13][14][15][16] From a rapidly growing number of experimental work on PTR detection of photoexcited carrier plasma waves in semiconductors it has become evident 10,13-15 that, unlike the PMR technique, for certain classes of materials, such as high-quality Si wafers, the plasma wave dominates the PTR signal. However, no quantitative analysis has been done yet regarding the relative sensitivity of the PMR and PTR methods to the thermal and plasma wave in semiconductors.…”

Noncontacting Photothermal Radiometry of MOS Capacitor Structures: The Frequency-Domain and DLTS Approaches

“…Both the PTR-FD and PTR-DLTS instrumentation set-ups used in the present study were described in detail previously [5,6]. An Ar+ Iaser emitting-1 W at 514 nm was used as an excitation source.…”

“…The noncontact method ofphotothermal infrared radiometry (PTR), with both frequency-domain (PTR-FD) [1][2][3] and rate-window (PTR-RW) [4,5] detection configurations has been shown to be promising for remote on-line or off-line impurity/electronic defect diagnostics. A new PTR deep-level transient spectroscopy (PTR-DLTS) which combines the PTR-RW with semiconductor temperature ramping has been developed recently [6] and found to possess high spectral peak separation and spatial resolution.…”

Time Varying Heat Conduction in Solids

“…The temperature variations could be detected directly using a pyroelectric transducer in the so called Photopyroelectric (PPE) method [Mandelis & Zver, 1985]. The sample's temperature oscillations can be also the cause of periodical black body infrared electromagnetic waves that are radiated by the sample and that can be measured using an appropriate sensor in the PT radiometry [Chen et al, 1993] In the photoacoustic (PA) method the sample is enclosed in a gas (example air) tight cell. The temperature variations in the sample following the absorption of modulated radiation induce pressure fluctuations in the gas, i.e.…”