A transistor is provided. The transistor includes a silicon layer including a source region and a drain region. A gate stack is disposed on the silicon layer between the source region and the drain region. The gate stack comprises a first layer of a high dielectric constant material, a second layer comprising a metal or metal alloy, and a third layer comprising silicon or polysilicon. A lateral extent of the second layer of the gate stack is substantially greater than a lateral extent of the third layer of the gate stack. Also provided are methods for fabricating such a transistor.