Book Description

Germanium (Ge) has emerged as a sound substitute for silicon in many next-gen semiconductor technologies in both electronic and optical devices due to high carrier mobility as well as high stopping power. Low resistivity n-type and p-type ohmic contacts are essentials for high performance Ge based devices and circuits. Germanium based devices has the complications of Fermi-level pinning in both the n-type and p-type contacts, constrained the use of two differing contacts in these devices. Current literature suggests using an interfacial layer to decrease the Schottky barrier height and to achieve near ohmic behavior of both n-type and p-type germanium. In this research different combination of metal/interlayer combinations for ohmic contacts to n-type as well as p-type Germanium were investigated, mask for test structures were designed using klayout tool and test devices structures have been fabricated on homoepitaxially grown p-type germanium(anode) and n-type germanium(cathode). These test devices which includes CTLM, TLM and Four-Terminal contact resistance method have been characterized using parametric analyzer, I-V behavior has been studied and specific contact resistivity has been calculated. Many of the tested metal/interlayer combination shows near ohmic behavior and others shows rectifying behavior. Also, defect decoration of the Surface is done on all the three different samples: p-i-n, anode(P+) and cathode(n+) to see if there is significant defect occurred on the surfaces of homoepitaxially grown Ge layers. Nomarski imaging showed no significant defect on the surface which strengthen the point that surface of homoepitaxially grown germanium is defect free.