Combination of X-ray diffractometer and solid state detector and method of use thereof

A combination of X-ray diffractometer and solid state detector is much faster than previous diffractometers and detectors in that X-ray photons that impinge on the detector do not have to be counted in the single photon counting mode.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a combination of an X-ray diffractometer and a 
solid state detector and to a method of use thereof. 
2. Description of the Prior Art 
X-ray diffractometers are known and previous diffractometers have used 
scintillation or proportional gas X-ray detectors (see paper by Halliwell, 
et al. entitled "Assessment of Epitaxial Layers by Automated Scanning 
Double Axis Diffractometry", Journal of Crystal Growth 65, (1983), pages 
672-678 and paper by Hart entitled "Characterization of Crystal Growth 
Defects by X-ray Methods", Plenum Press, (1980), pages 474-496). The 
detectors of previous diffractometers are employed in a single photon 
counting mode and use an indirect method of converting the X-ray energy 
into electrical pulses. One disadvantage of previous diffractometers is 
that it takes a relatively long period of time to take measurements, 
particularly at low intensities of an X-ray beam. Often, a large number of 
measurements must be taken. On pages 674 and 675 of the Halliwell 
reference, it is stated that area scans are usually performed on a 2 mm 
grid extending up to the maximum scannable area of 25.times.25 mm. The 
reference states that this can usually be completed in an overnight run. 
The reference further states that a counting time of about 5 seconds per 
point of the rocking curve is required and that data collection times of 
several minutes at each position on the sample are typical. Attempts have 
been made to improve the speed of scintillation detectors and counting 
circuits (see reference Bede Scientific Application Note #4 entitled 
"Design and Applications of the Enhanced Dynamic Range (EDR) Detector", 
January, 1992). 
While solid state detectors are known, they have previously been used for 
ultraviolet measurements in astronomy and have not been combined with 
diffractometers. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a combination of an 
X-ray diffractometer and solid state detector, which can increase the 
measurement speed over prior art diffractometers and detectors by a factor 
of 5 or greater. 
A combination of X-ray diffractometer and solid state detector has a high 
gain current to voltage conversion circuit, said circuit producing an 
analog voltage which is proportional to a number of X-ray photons which 
impinge on said detector with time when the detector is placed in a path 
of photons from an X-ray beam. 
A method of measuring X-ray intensity uses a multi-crystal X-ray 
diffractometer having a solid state detector. The method comprises 
locating said detector in a path of photons from an X-ray beam, taking 
measurements of the number of photons that impinge on said detector with 
time and producing a result of said measurements. 
A multi-crystal X-ray diffractometer has a high gain current to voltage 
conversion circuit in a solid state detector. The circuit produces an 
analog voltage which is proportional to the number of X-ray photons which 
impinge on the detector with time when said detector is placed in a path 
of photons from an X-ray beam.

DESCRIPTION OF A PREFERRED EMBODIMENT 
A solid state semiconductor detector which is sensitive to lower energy (or 
soft) X-rays is described in a paper by Canfield, et al. entitled "Silicon 
Photodiodes Optimized for the EUV and Soft X-ray Regions", SPIE, Vol. 
1344, EUV, X-ray and Gamma-Ray Instrumentation for Astronomy (1990). 
Preferably, the solid state semiconductor detector is made of silicon but 
other types of semiconductor materials may be suitable. 
One advantage of a solid state semiconductor detector is that the detection 
efficiency is much larger at lower X-ray energies, which are the normal 
energies used in X-ray diffractometers (see graph in data sheet and 
specifications of AXUV-1000, International Radiation Detectors). 
By employing a solid state semiconductor detector as the detector in an 
X-ray diffractometer further advantages are achievable. The detector can 
be employed in a high gain current of voltage conversion circuit which is 
much simpler in design than the normal scintillation counter circuit. This 
circuit produces an analog voltage which is proportional to the number of 
X-ray photons which impinge on the detector per second (i.e. a true 
measurement of X-ray intensity in real time without the dead time problems 
associated with scintillation counters). Thus, a measurement of X-ray 
intensity can be made much more rapidly and a complete data set can be 
generated in much less time than previous X-ray counting detection 
systems. Increases in speed of measurement by a factor of 5 or greater is 
achievable over previous diffractometers using scintillation counters. All 
references referred to herein are incorporated by reference in this 
application.