Figure 9. Infrared response spectra obtained from five lithium-drifted germanium diodes fabricated from crystals from five different sources [(1) - (5)] and four diodes fabricated from specimens of another crystal treated in known manners [(A) - (D)]. (Spectral features of interest as indicated by short vertical lines are identified in table 1. The diodes are identified in table 2.) [14]. Figure 10. Infrared response spectra of a commercial lithium-drifted silicon detector obtained before (A) and after (B) irradiation with fast neutrons [9]. Figure 11. detectors. Infrared response spectra of three commercial lithium-drifted silicon (Large peaks, similar to that in the spectrum of NBS-6S shown in figure 10, occur at 1.03 eV in the spectra of NBS-3S and NBS-4S. These are not shown because they exceed the scale of the figure.) [9]. NBS-4S 0.97 0.99 NBS-5S NBS-6S 1.03 Bx5 B Figure 12. Energy level scheme comparing features detected in IRR measurements on germanium :: (A) with levels resulting from radiation or thermal damage (B). References are given in brackets Symbols used: V-vacancy, VV-divacancy, 0-oxygen, D-donor, Li-lithium [26]. Figure 13. Energy level scheme comparing features detected in IRR measurements on silicon dioces (A) with levels resulting from radiation damage (B). References are given in brackets. used: V-vacancy, WV-divacancy, 0-oxygen, D-donor, Li-lithium [26]. Symbols -114A (REV. 7-73) U.S. DEPT. OF COMM. IBLIOGRAPHIC DATA SHEET ITLE AND SUBTITLE 1. PUBLICATION OR REPORT NO. 2. Gov't Accession 3. Recipient's Accession No. NBS-SP-400-13 Semiconductor Measurement Technology: mproved Infrared Response Technique for Detecting Defects nd Impurities in Germanium and Silicon p-i-n Diodes 5. Publication Date 6. Performing Organization Code Sponsoring Organization Name and Complete Address (Street, City, State, ZIP) J. S. Atomic Energy Commission Division of Biomedical and Environmental Research 20545 SUPPLEMENTARY NOTES Library of Congress Catalog Number: 75-1210 13. Type of Report & Period Covered Final 14. Sponsoring Agency Code ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant bibliography or literature survey, mention it here.) An infrared response (IRR) technique was evaluated for its utility in qualifying germanium for radiation detector use. Because of several improvements in the sensitivity and interpretation of the technique made during the evaluation, it was possible to observe a number of discrete energy levels lying within the forbidden energy gap of germanium which had passed unobserved in previous studies. These levels correlate with the type of defects and vacancies introduced by radiation damage into germanium as measured using such techniques as photoconductivity and Hall effect measurements after irradiation. Furthermore, the improved infrared response measurement method was used to identify impurities, such as copper, gold, and iron, and dislocations resulting from heat treatments in germanium. A major advance was made when it was determined that the IRR spectra could be grouped into five distinct types on the basis of spectral features observed in the energy range from 0.6 to 0.7 eV. One of the spectrum types represented crystals from which good quality detectors could be fabricated; the other four represented crystals that yielded poorer quality detectors due to carrier trapping, or crystals that presented problems such as low lithium drift mobility in detector fabrication. Three of the four spectrum types representative of poor crystal quality could be duplicated by suitably degrading specimens of a good quality crystal. The material and detector characteristics of crystals within each spectrum type were found to be similar. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons) Carrier trapping; gamma-ray detector; germanium; Ge (Li) detector; infrared response silicon. Announcement of New Publications on Semiconductor Measurement Technology Superintendent of Documents, Government Printing Office, Dear Sir: Please add my name to the announcement list of new publications to be issued in the series: National Bureau of Standards Special Publication 400-. |