Characteristics of Microwave Plasma and Preparation of a-Si Thin Film

Abstract

The characteristics of a plasma produced by launching 2.45 GHz microwave beams through a glass of pure argon gas have been studied. A direct observation of the microwave electric field with a loop antenna placed in the tube revealed that a plasma is produced at the microwave inlet. The threshold condition for a microwave discharge was experimentally obtained under a wide range of argon gas pressures and magnetic fields. The threshold gas pressure strongly decreases as the magnetic field approaches the electron cyclotron resonance (ECR) condition. By mixing SiH₄ gas (20%) with argon gas, an amorphous silicon thin film can be prepared in the microwave plasma. The impurity content and the morphology of the film depend on the substrate location.