Si(Li) X-ray detectors are available today in the field of nuclear techniques. At present we have made a series of Si(Li) X-ray detectors with high resolution. The processing technology and performance of the detectors are described. The largest active area of the devices is 200 mm
2
with the best resolution (FWHM) of 216
eV
and an average resolution of 223 eV for 5.9 keV. The best resolution for 28mm