Deep-level transient spectroscopy system using a spectrum analyzer

Wang, C. D.; Lin, Hsiu-Hsia

doi:10.1063/1.328820

Cited by 10 publications

(2 citation statements)

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“…Wang et a/ [9] ont proposi une variante oti un analyseur de spectre remplace la detection synchrone. Ces auteurs peuvent alors mesurer les ampljtudes de la fondamentale et des premieres harmoniques def(t, T).…”

Section: Introductionunclassified

FTDLTS: a novel isothermal DLTS method using Fourier transforms

Bloa¹,

Quan²,

Guennouni³

1993

Meas. Sci. Technol.

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Resume. Nous pr6sentons une nouveile methode isotherme de caracterisation des d6fauts profonds dans les semiconducteurs Dans cette methode, appeibe FTDLTS (Fourier transform deep-level transient spectroscopy), ie transitoire de capacite considere comme multi-exponentiel est decompos6 en utiiisant deux transformees de Fourier. Le spectre obtenu est ensuite ajuste aux moindres carres par une somme de gaussiennes. Nous decrivons Bgalement les solutions adoptees pour effectuer ie caicui numerique des transformees de Fourier ainsi que la mise oeuvre automatique pilotee par micro-ordinateur de la m6thode. La comparaison des spectres obtenus a partir des mgmes signaux synthhtishs bruit& et non bruites par cette methode et par deux methodes OLTS classiques est presentee. Grace a son meiileur pouvoir separateur, ia methode FTOLTS permet une bonne caracterisation des defauts profonds ayant des constantes de temps voisines. Cette methode est appiiquee a la caracterisation des niveaux profonds d'un bchantilion de GaAs multi-implant6 en oxygene et recuit a 650 ' C.

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Section: Introductionunclassified

FTDLTS: a novel isothermal DLTS method using Fourier transforms

Bloa¹,

Quan²,

Guennouni³

1993

Meas. Sci. Technol.

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“…87 , and Wang et.al. 88 ) The method is based on the result that for a continuous exponentially decaying function, β /ω is given by:…”

Section: Appendix A: Fft Algorithm For Decay Constant Calculationmentioning

confidence: 99%

Modifications to a Cavity Ringdown Spectrometer to Improve Data Acquisition Rates

Bostrom¹

2000

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Cavity ringdown spectroscopy (CRDS) makes use of light retention in an optical cavity to enhance the sensitivity to absorption or extinction of light from a sample inside the cavity. When light entering the cavity is stopped, the output is an exponential decay with a decay constant that can be used to determine the quantity of the analyte if the extinction or absorption coefficient is known. The precision of the CRDS is dependent on the rate at which the system it acquires and processes ringdowns, assuming randomly distributed errors. We have demonstrated a CRDS system with a ringdown acquisition rate of 1.5 kHz, extendable to a maximum of 3.5 kHz, using new techniques that significantly changed the way in which the ringdowns are both initiated and processed.On the initiation side, we combined a custom high-resolution laser controller with a linear optical feedback configuration and a novel optical technique for initiating a ringdown.Our optical injection "unlock" method switches the laser off-resonance, while allowing the laser to immediately return to resonance, after terminating the unlock, to allow for another ringdown (on the same cavity resonance mode). This part of the system had a demonstrated ringdown initiation rate of 3.5 kHz. To take advantage of this rate, we developed an optimized cost-effective FGPA-based data acquisition and processing system for CRDS, capable of determining decay constants at a maximum rate of 4.4 kHz, by modifying a commercial ADC-FPGA evaluation board and programming it to apply a discrete Fourier transform-based algorithm for determining decay constants. The entire system shows promise with a demonstrated ability to determine gas concentrations for H 2 O with a measured concentration accuracy of ±3.3%. The system achieved an ii absorption coefficient precision of 0.1% (95% confidence interval). It also exhibited a linear response for varying H 2 O concentrations, a 2.2% variation (1σ) for repeated measurements at the same H 2 O concentration, and a corresponding precision of 0.6% (standard error of the mean). The absorption coefficient limit of detection was determined to be 1.6 x 10 -8 cm -1 (root mean square of the baseline residual). Proposed modifications to our prototype system offer the promise of more substantial gains in both precision and limit of detection. The system components developed here for faster ringdown acquisition and processing have broader applications for CRDS in atmospheric science and other fields that need fast response systems operating at high-precision.iii DedicationTo my wife, Alison, without whose continual support and encouragement I could never have come close to accomplishing this.To my daughter, Naomi, who has only ever known me to be a graduate student-may she always appreciate physics the way she does now.To my Dad, whom I think would have really liked to have seen this, and to myMom, who has been proud enough of me for both of them.iv

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Electrical and optical measuring techniques for flaw states

Blakemore¹

Defect Complexes in Semiconductor Structures

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Deep-level transient spectroscopy system using a spectrum analyzer

Cited by 10 publications

References 5 publications

FTDLTS: a novel isothermal DLTS method using Fourier transforms

FTDLTS: a novel isothermal DLTS method using Fourier transforms

Modifications to a Cavity Ringdown Spectrometer to Improve Data Acquisition Rates

Electrical and optical measuring techniques for flaw states

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