METHOD OF CONTROLLING FORBIDDEN BAND WIDTH OF SEMICONDUCTOR SUPERLATTICE

摘要

PURPOSE:To facilitate varying the forbidden band width of a compound semiconductor superlattice containing As continuously and forming parts which have forbidden band widths different from each other selectively in one substrate by a method wherein an insulating layer which is to be a passivation film is formed on a part of the surface of a semiconductor layer structure including the compound semiconductor superlattice and the layer structure is subjected to a heat treatment under an As4 pressure and the type of the insulating layer and the As4 pressure are varied. CONSTITUTION:An n-type Al0.3Ga0.7As cladding layer 2, an MQW active layer 3, a p-type Al0.3Ga0.7As cladding layer 4 and a p-type GaAs contact layer 5 are successively built up on an n+type GaAs substrate 1 by a molecular beam epitaxy(MBE) method to form a layer structure. An SiN layer is formed on a part of the surface of the layer structure as a passivation film 6 and the layer structure is subjected to a heat treatment in a sealed tube under an arsenic pressure about 20Torr. As a result, in the region to which the arsenic pressure is directly applied, passivation conditions given by the arsenic pressure are degraded and PL is shifted to 770-780nm. The shift rate of PL can be selected arbitrarily within a range about 760-810nm continuously by varying the arsenic pressure. On the other hand, the passivation effect of the SiN layer functions remarkably in the region under the passivation film and PL of a super-lattice is not varied so much and is 810-820nm so that the forbidden band width in this region can be reduced by the value corresponding to PL about 40nm.