Methods for preparing an epitaxial wafer having a gallium nitride epitaxial layer deposited on a semiconductor substrate

A method for preparing an epitaxial layer onto GaAs substrate comprising the steps of:

• supplying a first mixture of material gases comprising HCl and a second mixture of material gases comprising NH3 into a chamber heated by a heat source disposed outside of said chamber;
• forming GaCl by reacting metal Ga contained in a vessel in said chamber with HCl included in said first mixture of material gases;
• growing a buffer having a thickness in the range of 60 nanometers to 200 nanometers by vapor deposition on a GaAs substrate at a first temperature of 400-600° C. disposed in the chamber;
• improving crystallinity of the buffer layer by increasing substrate temperature from the first temperature;
• and
• supplying said first and second mixtures of material gases into said chamber in which the substrate is heated at a second temperature higher than said first temperature to grow a GaN layer on said buffer layer.

A method for preparing an epitaxial wafer comprising the steps of:

• supplying a first mixture of material gases comprising a metallorganic including Ga and HCl and a second mixture of material gases comprising NH3 into a chamber heated by a heat source disposed outside of said chamber;
• growing a buffer layer having a thickness in the range of 60 nanometers to 200 nanometers by vapor deposition on a GaAs substrate at a first temperature of 400-600° C. disposed in the chamber;
• improving crystallinity of the buffer layer by increasing substrate temperature from the first temperature;
• and
• supplying said first and second mixture of material gases into said chamber in which the substrate is heated at a second temperature higher than said first temperature to grow a GaN layer on said buffer layer.

A method for preparing an epitaxial wafer comprising the steps of:

• supplying a first mixture of material gases comprising HCl and a second mixture of material gases comprising NH3 into a chamber heated by a heat source disposed outside of said chamber;
• forming GaCl by reacting metal Ga contained in a vessel in said chamber with HCl included in said first mixture of material gases;
• growing a buffer having a thickness in the range of 60 nanometers to 200 nanometers by vapor deposition on a GaAs substrate at a first temperature of 400-600° C. disposed in the chamber,
• improving crystallinity of the buffer layer by increasing substrate temperature from the first temperature;
• and
• supplying said first and second mixtures of material gases into said chamber in which the substrate is heated at a second temperature higher than said first temperature to grow a GaN layer on said buffer layer.

A method for preparing an epitaxial layer onto GaAs substance comprising the steps of:

• supplying a first mixture of material gases comprising a metallorganic including Ga and HCl and a second mixture of material gases comprising NH3 into a chamber heated by a heat source disposed outside of said chamber;
• growing a first GaN layer having a thickness in the range of 60 nanometers to 200 nanometers by vapor deposition on a GaAs substrate at a first temperature of 400-600° C. disposed in the chamber;
• growing a second GaN layer having a thickness in the range of 0.1 micrometers or more having improved crystallinity of the buffer layer due to increasing substrate temperature from the first temperature, and
• supplying said first and second mixture of material gases into said chamber in which the substrate is heated at a second temperature higher than said first temperature to grow said first and second GaN layers on said buffer layer.