Low resistance ohmic contacts are tremendously important for optoelectronic applications of all types. Formation of such contacts often requires high temperature (> 400°C) annealing to either form an alloy between the metal-semiconductor interface or to evaporate conductivity-limiting organics suspended in conductive pastes.
Formation of low resistance ohmic contact readily at lower temperatures can broaden optoelectronic devices to include thermally sensitive layers, which include but are not limited to flexible, thin, lightweight wearable printed electronics fabricated on polymer or cloth substrates, inexpensive customizable LEDs printed on paper, and higher efficiency solar cells. Such solar cells are currently limited by high series resistance. Series resistance in a solar cell comes from the resistance of (1) the semiconductor, (2) the semiconductor/metal interface, and (3) the metallic contact.
This work aims to optimize low-resistance ohmic contacts by either forming highly conductive electrodes at temperatures as low as room temperature with inkjet printing of reactive silver inks, or by rapidly and selectively annealing only the metallization by electromagnetic induction contact annealing.