JPS6424487A - Semiconductor light emitting device - Google Patents

Abstract

PURPOSE:To improve injection of carriers into a well in efficiency so as to decrease a threshold current and improve a luminous efficiency by a method wherein a forbidden band width of a barrier layer of a multiquantum well structure is made equal to or larger than the minimum that of a buffer layer. CONSTITUTION:A multi-quantum well structure 14 is provided between clad layers 12 and 16 through the intermediary of buffer layers 13 and 15, and the forbidden bandwidth ECL of the clad layers 12 and 16, the minimum that EBU, MIN of the buffer layers 13 and 15, and those EBA and EWE of a barrier layer 14b and a well layer 14a of the multi-quantum well structure 14 are determined so as to satisfy the following inequalities, ECL>EBU, MIN, EBA>EWE, and ECL>=EBA>=EBU, MIN>=EWE. That is, the forbidden bandwidth of a barrier layer of a multi-quantum well structure is made larger than that of a buffer layer when the buffer layer is uniform in composition, and larger than the minimum that of a buffer layer when the buffer layer is gradient in composition, so as to make a barrier layer higher than a buffer layer in barrier. By these processes, the injection of carriers into a well layer is improved in efficiency.