Quartz Crystal Monitor QCM

• Quartz crystal microbalance for thin-film measurements
• Compatible with most oscillator devices
• Mounting Flange DN40CF (2.75” O.D.), rotatable
• Linear travel 150 mm, 200 mm or 250 mm
• Bakeable up to 250°C

Introduction

This standard quartz crystal microbalance can be used for in situ flux calibration in many MBE applications. Due to the linear travel it is possible to move the quartz directly under the substrate for accurate rate measurements.

The main component is a gold plated piezo crystal which oscillates with its natural frequency. If material hits the quartz surface and sticks there the mass of the quartz will change. The change of mass results in a change of the natural frequency which will be detected.

The QCM instrument enables the measurement of thickness changes in the range of sub atom layers, i.e. < 1 nm. To overcome disturbing temperature effects the QCM is water cooled.

Application

Typical applications for the QCM Quartz Crystal Monitor are:

•   Flux calibration of effusion cells with regard to the cell temperature

•   Uniformity measurements using the linear travel to measure the flux rate at different positions

•   In-situ thickness control during the MBE process

Technical Data

Dimensions

E represents the internal length of the linear travel. S represents the available linear travel.
L is defined for the situation of fully retracted linear shift as pictured in the drawing.

The lenght E varies with the maximum shift S. Please choose from the following table:

Specific data

For general information on CF mounting flanges see Flange and Gasketdimensions .

Product code: e.g. **QCM 40-200-L100D35 ** is a quartz crystal monitor on DN40CF-flange with 200 mm shift, integrated water cooling , retracted in-vacuum length L = 100 mm and extended length S+L = 300 mm. The center of the active quartz surface is located at S+L-13 mm = 287 mm.
The surrounding tube has to have an inner diameter ≥35 mm.