Molybdenum Oxide MoO3 Evaporation Process Notes
Molybdenum oxide is a chemical compound with a chemical formula of MoO3. It is white to pale yellow in color with a melting point of 795°C, a density of 4.69 g/cc, and a vapor pressure of 10-4 Torr at ~900°C. It is primarily used to manufacture pure molybdenum metal. It is evaporated under vacuum to make transparent electrodes for photovoltaic cells.
Molybdenum Oxide MoO3 Specifications
|Material Type||Molybdenum Oxide|
|Color/Appearance||White to Pale Yellow, Crystalline Solid|
|Melting Point (°C)||795|
|Theoretical Density (g/cc)||4.69|
|Type of Bond||Indium, Elastomer|
|Thermal Evaporation Techniques||
Crucible: Al2O3, BN
|Temp. (°C) for Given Vap. Press. (Torr)||10-4: ~900|
|Comments||Slight oxygen loss.|
** The z-ratio is unknown. Therefore, we recommend using 1.00 or an experimentally determined value. Please click here for instructions on how to determine this value.
Empirical Determination of Z-Factor
Unfortunately, Z Factor and Shear Modulus are not readily available for many materials. In this case, the Z-Factor can also be determined empirically using the following method:
- Deposit material until Crystal Life is near 50%, or near the end of life, whichever is sooner.
- Place a new substrate adjacent to the used quartz sensor.
- Set QCM Density to the calibrated value; Tooling to 100%
- Zero thickness
- Deposit approximately 1000 to 5000 A of material on the substrate.
- Use a profilometer or interferometer to measure the actual substrate film thickness.
- Adjust the Z Factor of the instrument until the correct thickness reading is shown.
Another alternative is to change crystals frequently and ignore the error. The graph below shows the % Error in Rate/Thickness from using the wrong Z Factor. For a crystal with 90% life, the error is negligible for even large errors in the programmed versus actual Z Factor.