Improvements in method and apparatus for determining minority carrier diffusion length
The constant-magnitude steady-state surface photovoltage (SPV) method for determining the minority carrier diffusion length L is in principle an excellent technique. It has, however, recevied relatively limited use because of practical difficulties in carrying out the required measurements. This paper describes an improved measurement system that virtually eliminates these difficulties and allows a rapid straightforward determination of L. These measurements in silicon monitor wafers have enabled a routine quality control check on many factory processing steps, particularly those that are carried out at high temperature and have the potential for significantly degrading L.
A Method for the Measurement of Short Minority Carrier Diffusion Lengths in Semiconductors
A method is presented whereby short minority carrier diffusion lengths in semiconductors may be determined by measuring the variation of surface photovoltage as a function of optical absorption coefficient. The method does not depend upon the specific form of the relationship between the surface photovoltage and the density of the excess minority carriers injected at the bulk edge of the surface space charge region. Only capacitive contacts to the sample are needed for the measurement. The method has been used to determine the minority carrier diffusion length in both n and p type gallium arsenide.
Mechanical behaviour and durability of high volume fly ash cementitious composites
The purpose of this research is to separate different morphological particles of ASTM class F fly ash, and study their effect on mechanical behaviour and durability of high volume cementitious mixtures. In this research wet separation of raw fly ash is carried out, which resulted in three layers of different morphological particles. The first layer of particles float, comprise of about 1-5% of fly ash, is identified as cenospheres or hollow spheres. The second layer of particles is measured to be 55-60% of raw fly ash and consisting of porous spherical and rounded particles rich in Si and Al. The third layer particles is measured to be about 35-40% of raw fly ash. High volume fly ash cementitious composites containing second or third layer particles are tested under compression and bending, highlighting a higher strength and ductility in comparison to cementitious ones containing raw fly ash particles. KEYWORDS. Cementitious matrix; Raw fly ash; Second layer particles; Third layer particles.