When GaN and related materials (such as AlN, AlGaN, and InGaN) are exposed to air, an oxide layer forms on the surface. As a result, the oxidized surface exhibits a decreasing luminescent efficiency and degrades the performance of certain electronic and opto-electronic devices based on GaN semiconductors. This effect also limits the quality of ohmic contacts made on this material, especially on p-type GaN and related materials. Devices in which these problems can be significant include AlGaN/GaN heterostructure field-effect transistors (HFET's), GaN junction field-effect transistors (JFET's), GaN metal-insulator-semiconductor field-effect transistors (MISFET's), GaN metal-semiconductor field-effect transistors (MESFET's), GaN light-emitting diodes, GaN laser diodes, GaN photodetectors, and negative electron affinity photocathodes based on AIN.In recognizing this problem, researchers at Arizona State University have developed a specific chemical treatment stabilizing GaN semiconductor surfaces. Application of the passivation technique has been shown to improve photoluminescent (PL) intensity by a factor of three to four even after three months. Additionally, it has been determined that the method can increase Schottky barrier hieght of n-type GaN by more than 50% (e.g. up to ~1.70 eV) thus reducing leakage current leading to improved transistor perfromance. The discovery also implies large potential improvements to ohmic contacts on p-type materials. This technique is applicable to the laser facets of GaN-based structures; the manufacture of heterojunction bipolar transistors or light-emitting diodes (LED's). This treatment can improve laser reliability, transistor gain, and LED light emission efficiency. It can also be useful to stabilize the GaN or AlGaN surface in many other devices, such as field-effect transistors. Other applications of this technique could include improving ohmic contacts on GaN and related materials or to metal-insulator-semiconductor (MIS) structures based on GaN, AlGaN/GaN, AlGaN/InGaN, or GaN/InGaN semiconductors.
|Original language||English (US)|
|State||Published - Jan 1 1900|