Amorphous Semiconductor Devices: Memory and Switching Mechanism

Abstract

This paper reports the study of amorphous semiconductor devices of memory and threshold types. Measurements have been made on As Ge₁₀ Te_90- glasses, silver dpoed As₁₀ Ge₁₅ Te₇₅ glass with silver concentrations from 0 to 10.0 at.% and Se₂₀ Ge₂₀ Te₆₀ and Se₂₀ Ge₂₀ T₅₅ glasses. The I—V characteristics in the OFF state of the materials have been studied at temperature 30,50, 60, 80 and 100°C. The threshold voltages of switching and their variation with temperature, composition and silver content have been studied. Measurements reveal that (i) the I—V characteristics over a wide range of temperature can be normalized into a single curve, (ii) the threshold voltage of switching decreases exponentially with the increase of temperature, (iii) the ratio of activation energy of dc conductivity to that of switching is of the order of two for all these glasses, (iv) the threshold voltage of switching is well correlated with the glass transition temperature, (v) Silver doping does not change the basic behaviour of As-Ge-Te glasses, and (vi) the switching mechanism in both memory and threshold devices studied, appears to be initiated by a thermal process with possible electronic contribution.

Indexing Terms:

• Amorphous Semiconductors
• Switching Devices
• Memory and Threshold Switch

Additional information

Notes on contributors

K.N. Lakshminarayan

Lakshminarayan, K N (Dr): (b. 1936 Sep. 25). Received MSc from Vikram University in 1959 and PhD from IISc, Bangalore in 1965e He is working as Reader in the Physics Department, Panjab University, Chandigarh since 1966. Before joining Panjab University, he had worked at National Physical Laboratory (1966) and the Indian Institute of Science (1961–66) and Vikram University (1960–61). His fields of interest are, Electron devices, Solid-State Physics and Communication. He has published over 20 research papers. He is Fellow IETE and Member of Indian Physics Association and National Academy of Science, India.

K.K. Srivastava

Srivastava, K K (Dr): (b. 1933 Sept. 5). Received PhD and DSc degrees from Allahabad University in the years 1958 and 1976 respectively.

He visited University of South Carolina, Columbia, USA as a post doctoral fellow from 1958–60 and University of Toronto, Canada, from May 1970 to December 1971. She 1963, he has been on the faculty of department of Physics at Panjab University, Chandigarh.

Dr. Srivastava's present research interest is in the area of amorphous semiconductors. He has produced four PhD's and has published fifty research papers. He is a member of the Society of Sigma Xi, and a member of the National Academy of Science.

O.S. Panwar

Panwar, O S: (b. 1954 Mar. 15). Obtained BSc with I class and Hons, and MSc in Physics (Solid State) with class securing 2nd position from Meerut University, Meerut in 1973 and 1975 respectively. The topic of his PhD thesis submitted to Panjab University (1979) is Electrical Properties of Pure and Doped Glasses of As-Ge-Te. Since 1975, working as a Research Fellow of CSIR in the Department of Physics, Panjab Univeristy, Chandigarh. He has published over 10 research papers. His areas of interest are Solid-State Physics and Electron Devices.

A. Kumar

Kumar, A: (b. 1954 January 9), Passed MSc in Physics with first division in 1974 from Agra University. Since Jan. 1976 working as a Research Fellow of CSIR. Submitted his PhD thesis on ‘Electrical, Dielectric and Switching Behaviour of Some Amorphous Semiconductors' to Panjab University in Aug. 1979. His fields of interest are Solid-State Physics and Electronics.