Fundamentals of junction measurements in the study of deep energy levels in semiconductors

Grimmeiss, H. G.; Ovrén, C.

doi:10.1088/0022-3735/14/9/002

Cited by 92 publications

(9 citation statements)

References 19 publications

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“…We will now continue to discuss how the properties of these buried nanometer-sized Schottky contacts may be investigated, and in particular we will present the use of space-charge techniques 22 to obtain detailed information about the electron kinetics of buried metal features on a floating potential. We will now continue to discuss how the properties of these buried nanometer-sized Schottky contacts may be investigated, and in particular we will present the use of space-charge techniques 22 to obtain detailed information about the electron kinetics of buried metal features on a floating potential.…”

Section: Nanometer-sized Contactsmentioning

confidence: 99%

Epitaxially overgrown, stable W–GaAs Schottky contacts with sizes down to 50 nm

Wernersson

Georgsson

Gustafsson

et al. 2002

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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A processing scheme for the fabrication of embedded W–GaAs contacts has been established and the resulting contact characteristics have been evaluated. The main advantage of these contacts is that they are stable during high-temperature epitaxial overgrowth. The fabrication scheme is based on a liftoff process with electron beam evaporation of tungsten and subsequent epitaxial overgrowth using metalorganic vapor phase epitaxy. Various methods were used to characterize the buried contacts. First, the structural properties of GaAs surrounding embedded W features, with widths down to 50 nm, were characterized by high-resolution transmission electron microscopy. Measurements of the conductivity in individual, buried wires were performed in order to study the influence of the overgrowth process on the properties of the tungsten. We also evaluated the current–voltage characteristics for macroscopic contacts, which revealed a clear dependence on processing parameters. Optimized processing conditions could thus be established under which limited contact degradation occurred during overgrowth. Finally, we used the overgrowth technique to perform a detailed investigation of the electrical and optical properties of floating-potential embedded nano-Schottky contacts by space-charge spectroscopy.

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Section: Nanometer-sized Contactsmentioning

confidence: 99%

Epitaxially overgrown, stable W–GaAs Schottky contacts with sizes down to 50 nm

Wernersson

Georgsson

Gustafsson

et al. 2002

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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“…The simplicity of the experiment is attractive compared to dual-source steady-state photocurrent methods that require multiple excitation sources and to transient photocurrent studies that determine the optical emission rate directly. 17 The method employed here is found to be robust against unusual photocurrent behavior that likely stems from the nonideal Schottky diode characteristics concomitant with deep dopants such as Mg in GaN. The theoretical basis for the present methodology is briefly reviewed, followed by an analysis of a͒ Author to whom correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%

“…However, the interpretation of the diode admittance can be ambiguous when the dopant itself behaves as a deep level,8 as is the case for p-type ͑Al͒GaN:Mg. Spectral photocurrent has been applied to p-type GaN:Mg ͑Ref. 14͒ but is not able to distinguish majority and minority photoemission processes and thus cannot resolve deep level energies quantitatively 17. as a convenient and powerful method for quantitative investigation of deep levels in wide bandgap materials with deep dopants.…”

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confidence: 99%

Deep level investigation of p-type GaN using a simple photocurrent technique

Armstrong

Thaler

Koleske

2009

Journal of Applied Physics

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Effects of interface states and temperature on the C -V behavior of metal/insulator/AlGaN/GaN heterostructure capacitorsThe deep level spectrum of p-type GaN was investigated using time-resolved photocurrent spectroscopy. The spectral dependence of the optical cross section for hole photoemission from a deep level was determined from the initial value of the photocurrent transient. Unlike other implementations of photocurrent, the present method does not require multiple excitation sources or determination of the optical emission rate. A deep level was observed at E v + 1.84 eV, where E v is the valence band maximum, with a Franck-Condon shift of 0.25 eV. A bias-dependent component of the photocurrent, possibly due to metal-semiconductor interface states, complicated the steady-state response but did not affect the measured spectrum for the E v + 1.84 eV deep level. This photocurrent method is expected to be readily extended to materials with very deep dopants, such as p-type AlGaN, for which many other deep level spectroscopy techniques are unsuited.

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“…It was pointed out that there is a considerable difference in the ionization energy and trapping cross section of some of the deep centers, according to the data obtained by different researchers. It was pointed out [6] that since the population of the deep levels in NDLS is completely defined by the charge carder emission processes when the barrier structure is switched from the equilibrium state into the depletion state, the results obtained by this method cannot give direct information on the parameters of the trapping processes. It was pointed out [6] that since the population of the deep levels in NDLS is completely defined by the charge carder emission processes when the barrier structure is switched from the equilibrium state into the depletion state, the results obtained by this method cannot give direct information on the parameters of the trapping processes.…”

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confidence: 99%

Determination of the parameters of deep levels in semiconductors using nonstationary spectroscopy and low-frequency noise spectroscopy

Kholomina¹

1998

Meas Tech

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A development of the activation-drift model is obtained. This enables the procedure for determining the parameters of deep levels in semiconductors using the data of nonstationary spectroscopy and low-frequency noise spectroscopy to be made more accurate and increases the reproducibility and reliability of the results of measurements.Deep levels in semiconductors, localised in the forbidden-energy gap, have a consideable effect on the properties of materials and on the devices made from them. Hence, the problem of investigating the parameters of deep levels produced by different types of structural defects, and also of the physical processes which occur when they are recharged is of particular importance. Nonstationary (relaxational) deep-level spectroscopy (NDLS, including DLTS) and low-frequency noise spectroscopy are promising methods of determining the parameters of deep levels: the ionization energy AE and the density N r Capacitive NDLS involves measuring the relaxation of the capacitance when a reverse bias U is applied to the semiconductor structure with an asymmetrical p-n-junction or a Schottky barrier. A characteristic feature is the requirement for a fairly high depleting bias U on the barrier structure, which must ensure that mobile carriers, emitted from the deep level, are removed from the space-charge region. Temperature scanning enables the maxima of the NDLS signal to be recorded with relaxation times t that are characteristic for each type of deep center (trap) and which are identical with the specified length of the measuring reverse-bias pulse (the NDLS "window").To investigate the parameters of deep levels by the low-frequency noise spectroscopy method in barrier structures, the spectrum or temperature dependence of the spectral power density of the low-frequency noise is used as the response function.To determine the parameters of deep levels, the maxima of the temperature dependences of the spectral power density or characteristic inflection frequencies (changes in slope) of the low-frequency noise spectra are used when ~bx = 1, where ~t, is the angular frequency corresponding to the inflection or maximum and x is the relaxation time of the process.To describe relaxation processes having an activation nature, an expression of the following form is often used:where x o is a factor which has different physical meanings in different models, AE is the ionization energy, k is the Boltzmann's constant, and T is the absolute temperature. The exponential factor in (1) (the Boltzmann exponent) represents the emission (generation) parameters of the carriers. The slope of the Arrhenius curves Ig~ = ~p(T-l), constructed from the experimental results of investigations of the NDLS curves or the temperature dependences of the spectral power density of the low-frequency noise, enables the ionization energy of a deep center z~ in (1) to be determined.Many theoretical and experimental publications on NDLS and low-frequency noise spectroscopy are based on an approach that is common to all these methods, deve...

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Fundamentals of junction measurements in the study of deep energy levels in semiconductors

Cited by 92 publications

References 19 publications

Epitaxially overgrown, stable W–GaAs Schottky contacts with sizes down to 50 nm

Epitaxially overgrown, stable W–GaAs Schottky contacts with sizes down to 50 nm

Deep level investigation of p-type GaN using a simple photocurrent technique

Determination of the parameters of deep levels in semiconductors using nonstationary spectroscopy and low-frequency noise spectroscopy

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