Electronics and Telecommunications Research Institute

Chul Won Ju

Dae Woo Lee

Jae Kyoung Mun

Jong Min Lee

Sang Choon Ko

Ho Young Kim

Seong Il Kim

Byoung Gue Min

Kyung Ho Lee

Kyu-Seok Lee

Yong Il Jun

The inventive concept relates to a system supplying a constant current direct current power to serial loads connected in series with one another. The inventive concept is constituted by a constant current source power supply unit outputting a predetermined direct current, a load connection unit having the same rated current characteristic as the constant current source, a load connection unit having a rated current characteristic smaller than the constant current source, a load connection unit having a rated current characteristic greater than the constant current source, a load connection unit having a rated current characteristic greater or smaller than the constant current source and a circuit controlling or protecting them.

Serial loading constant power supply system

Provided is a method of fabricating a heterojunction bipolar transistor (HBT). The method includes: sequentially depositing a sub-collector layer, a collector layer, a base layer, an emitter layer, and an emitter capping layer on a substrate; forming an emitter electrode on the emitter capping layer; forming a mesa type emitter to expose the base layer by sequentially etching the emitter capping layer and the emitter layer using the emitter electrode as an etch mask in vertical and negative-sloped directions to the substrate, respectively; and forming a base electrode on the exposed base layer using the emitter electrode as a mask in self-alignment with the emitter electrode. In this method, a distance between the mesa type emitter and the base electrode can be minimized and reproducibly controlled. Also, a self-aligned device with an excellent high-frequency characteristic can be embodied.

Method of fabricating heterojunction bipolar transistor

Growing community of inventors

Daejeon, South Korea

Chul Won Ju