Enhancement mode GaN HEMT device and method for fabricating the same

A method of forming an enhancement mode GaN transistor, the method comprising:

• nucleating and growing transition layers on a substrate;
• growing an InAlGaN EPI layer over the transistor layers;
• growing an InAlGaN barrier layer over the InAlGaN EPI layer;
• growing an InAlGaN layer with acceptor type dopants over the InAlGaN barrier layer;
• growing a GaN layer with acceptor type dopants over the doped InAlGaN layer;
• depositing a gate contact layer on the doped GaN layer
• applying a gate photo resistant pattern;
• etching away the gate contact layer outside the gate region;
• etching away the doped GaN layer and the doped InAlGaN layer, except for portions of the doped GaN layer and the doped InAlGaN layer beneath gate contact;
• removing the gate photo resistant pattern;
• depositing a dielectric layer;
• applying a contact photo resistant pattern;
• etching the dielectric layer to open the drain and source contact area;
• removing the contact photo resistant pattern;
• depositing an Ohmic contact metal;
• applying a metal photo resistant pattern;
• etching the Ohmic contact metal;
• removing the metal photo resistant pattern;
• and
• performing rapid thermal annealing to form Ohmic drain and source contacts.

A method of forming an enhancement mode GaN transistor, the method comprising:

• nucleating and growing transition layers on a substrate;
• growing an InAlGaN EPI layer over the transistor layers;
• growing an AlGaN barrier layer over the InAlGaN EPI layer;
• growing an AlGaN layer with acceptor type dopants over the AlGaN barrier layer;
• growing a GaN layer with acceptor type dopants over the doped AlGaN layer;
• depositing a gate contact layer on the doped GaN layer
• applying a gate photo resistant pattern;
• etching away the gate contact layer outside the gate region;
• etching away the doped GaN layer, except for portions of the doped GaN layer and the doped AlGaN layer beneath gate contact;
• removing the gate photo resistant pattern;
• applying another photo resistant pattern;
• etching the doped AlGaN layer such that the doped AlGaN extends outside the gate region towards the drain;
• removing the photo resistant pattern;
• depositing a dielectric layer;
• applying a contact photo resistant pattern;
• etching the dielectric layer to open the drain and source contact area;
• removing the contact photo resistant pattern;
• depositing an Ohmic contact metal;
• applying a fourth photo resistant pattern;
• etching the Ohmic contact metal
• removing the fourth photo resistant pattern;
• and
• performing rapid thermal annealing to form Ohmic drain and source contacts.