ATOMIC LAYER EPITAXY : A NEW TOOL FOR NOVEL MODULATED SEMICONDUCTOR STRUCTURES

Abstract
A novel growth technique for III-V compounds, atomic layer epitaxy(ALE), is presented as having several advantages over such conventional growth methods as MBE, MOCVD and VPE. In ALE, a self-limiting growth mechanism works quite effectively. This mechanism makes it possible to grow layers accurately in monolayer units. Experimental results show that ALE growth using cloride source gases, such as GaCl and InCl, retains monolayer growth characteristics over a wide range of growth conditions. The present method is successfully applied to selective growth. Monolayer-unit growth takes place independent o f the ratio of window and masked region areas, and excellent selectivity is accomplished. Atomic-plane doping using Se as an impurity is demonstrated. Finally, delta-doped FET fabrication using Se atomic-plane doping is presented as the first ALE device application. The measured transconductance of the delta-doped FET with a 0.5 µm gate is 215 mS/mm and is comparable to that obtained from MBE-grown delta-doped(Si) FET. Interesting results obtained with ALE using metalorganic compounds as source gases of group III elements are also reviewed.