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InP polycrystal

The polycrystalline ingot is obtained by a Horizontal Gradient Freeze (HGF) which is the cooling of an InP Melt obtained by reaction between liquid indium and phosphorus vapour at 30 atmospheres. This method produces high purity, stoechiometric Indium Phosphide. The ingot is 300 mm long and the section is half of a 45 mm diameter. Each ingot weighs 1 250 g.

InP single crystal

The tCZ growth (modified Czochralski method) is used to pull a single crystal through a boric oxide liquid encapsulant starting from a seed. The dopant (Fe, S, Sn or Zn) is added to the crucible along with the polycrystal. High pressure is applied inside the chamber to prevent decomposition of the Indium Phosphide. InPACT has developed a process to yield fully stoechiometric, high purity and low dislocation density InP single crystal.

The tCZ technique improves upon the LEC method thanks to a thermal baffle technology in connection with a numerical modeling of thermal growth conditions. tCZ is a cost-effective mature technology with high quality reproducibility from boule to boule.

Some comparative technical data :

InP Wafer processing
Each ingot is cut into wafers which are lapped, polished and surface prepared for epitaxy. The overall process is detailed hereunder.

Flat specification and identification

The orientation is indicated on the wafers by two flats (long flat for orientation, small flat for identification). Usually the E.J. standard (European-Japanese) is used. The alternate flat configuration (U.S.) is mostly used for Ř 4" wafers.

Orientation of the boule

Either exact (100) or misoriented wafers are offered.

Accuracy of the orientation of OF

In response to the needs of the optoelectronic industry, InPACT offers wafers with excellent accuracy of the OF orientation : < 0.02 degrees. This feature is an important benefit to customers making edge-emitting lasers and also to manufacturers who cleave to separate dies – allowing their designers to reduce the “real-estate” wasted in the streets.

Edge profile

There are two common specs : chemical edge processing or mechanical edge processing (with an edge grinder).


Wafers are polished by means of a chemical-mechanical process resulting in a flat, damage-free surface. InPACT provides both double-side polished and single-side polished (with lapped and etched back side) wafers.

Final surface preparation and packaging

Wafers go through many chemical steps to remove the oxide produced during polishing and to create a clean surface with stable and uniform oxide layer that is ready for epitaxial growth - epiready surface and that reduces trace elements to extremely low levels (EPICLEAN ). After final inspection, the wafers are packaged in a way that maintains the surface cleanliness.
Specific instructions for oxide removal are available for all types of epitaxial technologies (MOCVD, MBE).


As part of our Statistical Process Control/Total Quality Management Program, extensive database recording the electrical and mechanical properties for every ingot as well as crystal quality and surface analysis of wafers are available. At each stage of fabrication, the product is inspected before passing to the next stage to maintain a high level of quality consistency from wafer to wafer and from boule to boule.

Please click on our standard specifications for numbers

Bulk quality:

Residual stress (X-ray diffraction) and Dislocations (EPD mapping).



Surface quality:

Contamination (TOF SIMS data), Roughness, Flatness (warp, TTV, LTIR...) and Particles.