Investigations of field effect transistors at cryogenic temperatures
Management Information Services, Jan 1, 1970 - Technology & Engineering - 73 pages
Various JFET and MOSFET devices have been studied at LN and L He temperatures. A strong increase in transconductance and decrease in equivalent input noise is registered when the ambient temperature changed from 300K to 77K. A very small change in electrical parameters of the device was noticed when the environment temperature was further lowered to 4.2K. Transient and steady state heating of the devices at 4.7K is investigated and it is found that the active part of the device heats up typically to a steady state value of 40 - 60K. In most of the devices this agrees with the thermal noise observed. A transient and steady state device heating model is constructed and the results are found to be in good agreement with the measured temperatures and measured heating transients. The equivalent input noise studies for a germanium FET device have shown a strong 1/F-noise for frequencies up to approximately 100 kHz and thermal noise for higher frequencies. At cryogenic temperatures JFET devices show a slight decrease in noise spectrum. The noise spectrum of the MOSFET devices in most cases is by an order of magnitude larger than that of the JFET device. Some of the MOSFET devices show a substantial increase in noise at lower frequencies when the environment temperature is lowered to a cryogenic level. (Author).
9 pages matching i-v characteristics in this book
Results 1-3 of 9
What people are saying - Write a review
We haven't found any reviews in the usual places.
FET Operation at 4 2K
Heating Effects in FET and MOSFET Devices
Investigation of Noise
1 other sections not shown
1/f noise 4.2 K environment ambient temperature amplifier boundary conditions calculated noise calculated thermal noise conduction band constant heat flux cryogenic environment cryogenic temperatures curve tracer decreasing temperature depletion region DSS DSS environment temperature Equivalent input noise Fermi energy FET operation FET's field effect transistors following parameters function g/cm Ge-substrate GeJFET Generation-Recombination Noise germanium heat diffusion equation heat flow equation heating time constant higher frequencies i-v characteristics increase initial condition input noise voltage interface temperature j/mole JFET kovar disk kovar wire larger liquid helium low noise preamplifier measured time constant MOSFET devices noise due noise spectrum obtain One-dimensional Slab p-n junction pinch-off voltage repetition rate shown in Fig Si-substrate single time constant solving the heat SRH centers Steady State Heating steady state temperature substrate temperature dependence Texas Instruments thermal conductivity trace transconductance transient heating uniform heating xn n xn xn n=l