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Nondestructive express-method of acoustic emission control and forecasting for stability and steadity to external influences of functional materials and structures

№ 17 The department  for problems of defect formation and nonequilibrium processes in complex semiconductors.
    A.I. Vlasenko O.V. Lyashenko, V.P. Veleschuk

Purpose - for use in areas of the industry
    The given method is passive ultrasonic nondestructive the express-method which allows to reveal in semiconductor materials and structures the beginning fast degradation processes at action of external fields of the different physical nature in a mode of real time.

 Principle of action.
    The method allows, unlike overwhelming majority of other quality monitoring of semiconductor materials, structures and devices, in a mode of real time without damage of the investigated sample to fix the beginning of process of intensive degradation due to formation structural defects or intensive processes of change of their energy condition at current passage, laser irradiation, deformations, machining, etc.
    The principle of action of development is based on the phenomenon of acoustic emission (АE) which means radiation of internal spontaneous acoustic wave’s noise character at local dynamic reorganization of solid state structure which is accompanied by formation and failure of mechanical pressures in local volumes at action of external fields of the different physical nature.
    For example, at use of pulse laser technologies the offered method allows to establish a surface melting threshold of functional materials and structures based on the semiconductor compounds.
    The features of development are following:
    At each value of external influence АE it is registered to operation of all potentially active (for the given influence) AE sources, i.e. to AE discontinuance.
• Necessity of unitary fastening (acoustic contact to the sample).
• The offered method completely is compatible for simultaneous use to the majority of other quality monitoring of materials and structures, except for use of an excited environment and acoustic radiation in a range of AE registration. The received information is partially complementary.
• At static and dynamic (ultrasonic) mechanical, and also other kinds of processing the method allows to receive the information on dynamics of development of elementary acts of plastic deformation in a mode of real time.
    The scope of the offered development can be expanded on other external influences, materials, structures and devices.

The basic technical and economic characteristics of development
Registration of AE signals to be carried out acoustoelectric sensors from the complete set dualchannel acousticemission device AF-15 which in strips of frequencies 20-200 кHz, 200-500 кHz and 500-1000 кHz have approximately identical relative sensitivity in the middle of a corresponding strip.
    Amplification (on 78...85 dB) and the previous processing of electric AE signals can be carried out AF-15 or by means of the similar device. The further processing and registration is carried out by a computer by means of the corresponding software.
    There is an opportunity of full automation of control process.
    The estimated cost of development, depending on the form of realization, makes from 10 000 up to 60 000 USD.