Room temperature spectroscopy of deep levels in junction structures using barrier capacitance charging current transients

Abstract

A technique is presented for room temperature spectroscopy of deep levels in semiconductor devices based on measurements of current transients due to barrier capacitance charging. Spectroscopic measurements are obtained from a set of the barrier capacitance charging current transients modified by illumination pulses with wavelength between 1.5 and 10 µm. Deep levels with activation energy in the range between 0.24 and 0.56 eV have been revealed in thyristor and neutron irradiated particle detector structures by using this technique.

Review—Carrier Lifetime Spectroscopy for Defect Characterization in Semiconductor Materials and Devices

“…A short excitation pulse with incident hν energy photons of surface density F(hν) integrated per pulse duration makes a δ-shape optical emission of trapped carriers, if hν fits to E d and the cross-section σ p-e of the photon-electron interaction is sufficiently large. The cross-section σ p-e for electrons located in deep levels is then described 33,34 by Lucovsky's expression: [32][33][34]…”

“…Similar spectroscopic arrangements can be employed for the analysis of deep traps in device structures by using pulsed capacitance probing via measurements of the barrier capacitance transients under linearly increasing voltage (BELIV) technique. 34,[37][38][39][40] Instrumentation for in situ examination of radiation defect evolution.-For defect spectroscopy, evolution of lifetime variations during processing or irradiations/implantation procedures can be a sensitive and non-invasive tool when using MW-PC and optical signal measurement systems. The additional signal transfer systems should be exploited for the in situ monitoring of the evolution of radiation defects when remote measurement equipment is employed for safety reasons, at a safe distance from harsh irradiation areas.…”

Comparative Study of Current Transients in HPHT and CVD Diamond Capacitor-Sensors

“…Pulsed signal waveforms, recorded using barrier evaluation by linearly increasing voltage (BELIV) technique, [10][11][12][13] directly indicate the type of structure: the triangular linearly increasing voltage (LIV) pulse is transformed into a square-wave waveform signal for a capacitor structure with blocking electrodes, while an electrode system with ohmic contacts maintains a triangular shape of the LIV pulse. The BELIV circuitry (Figure 2c)) contains an adjusted output of a generator of LIV, a device under test and a load resistor (R L ), connected in series.…”

“…The PG-1 forms a pulse of variable duration to handle the sequence of certain number of LIV pulses and, thus, the optical and electrical pulses are synchronized, as discussed in Ref. 13. Usually, a laser pulse is synchronized with the beginning of the first LIV pulse in a sequence and impacts the measured capacitance charging current transient due to diffusion/recombination of excited carriers.…”

“…In this work, the role of carrier recombination and ambipolar diffusion in formation of pulsed current signals has been examined by combining pulsed techniques of capacitor charging and sensor signal changes under external illumination, additionally to a comparative analysis of current transients in HPHT and CVD diamond capacitortype detectors. The techniques of the pulsed capacitor charging using linearly increasing voltage (BELIV) [10][11][12][13] and the microwave probed photoconductivity (MW-PC) transients have been complementary employed in this work for independent measurements of carrier lifetime as well as diffusion parameters and for separation of their role on manifestation of sensor characteristics. Profiling of current pulses has been performed by using two regimes: i) by varying the applied voltage after bulk injection of excess carriers; ii) by varying the position of the injected local domain within the inter-electrode gap, when the directions of the applied electric field and of the sharply focused laser beam are perpendicular.…”