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Lecture 16 Active Microwave Diodes
1. Transferred Electron Devices (TEDs)
• Gunn-Effect Diodes (GaAs Diods)
• InP Diodes
2. Avalanche Transit-Time Devices
• Read Diode
• IMPATT Diodes
• (BARITT Diodes)
Fundamental Different from FETs
• Bulk devices having no junctions or gates
• Compound semiconductors (GaAs or InP)
• TEDs operate with “hot” electrons whose energy is very much greater than the thermal energy.
• Ridley and Watkins proposed in 1961• Hilsum calculated the transferred electron effect in III-V in 1962; experiment fails.• J.B. Gunn of IBM discovered the so-called Gunn effect in 1963 and rejected the above theory.• Kroemer explained the origin of the negative differential mobility is
Ridley-Watkins-Hilsum’s mechanism
Magic Number : 3000V/cmMagic Number : 3000V/cm
Two-valley model theory
Homework:
High-field Domain Formation:High-field Domain Formation:
n+-p-i-p+
Read in 1958 (theory)Lee et al. 1965 (demonstration)
τ=L/vd
Homework:Read “Modern Semiconductor Device Physics” by SzeChapter 6 pp. 343-401
Scanned pdf file could be provided upon requests.
Due on November 30, 2010 (Tuesday)