High-frequency thin-film multijunction thermal converter on a quartz crystal chip

The design of a new planar or thin-film multijunction thermal converter (PMJTC) on a quartz membrane and a quartz crystal chip results in a calculable standard for ac-dc voltage transfer for frequencies from 100 kHz to 100 MHz with improved uncertainties. This is due to smaller dielectric losses and higher insulation resistance in the quartz membrane and the quartz chip. The window with the membrane is anisotropically etched into the quartz crystal chip. For the first measurements, the temperature of the heater was radiometrically sensed with a thin-film infrared sensor and later with an array of 100 Cu-CuNi thermocouples. At frequencies higher than 100 kHz, the ac-dc voltage transfer differences are one order smaller than with the standard PMJTC with the Si₃N₄/SiO₂/Si₃N₄ sandwich membrane on a silicon chip.