| 摘要 |
PURPOSE:To obtain an avalanche photodiode, which has an excellent guard ring effect and a low noise feature, by forming a light absorbing layer, a first multiplying layer having high carrier concentration, and a second multiplying layer having low carrier concentration constituting a P-N junction on the substrate surface wherein a concave part is provided, by a series of liquid phase epitaxial growth. CONSTITUTION:The concave part is formed in the light receiving part forming region of the N<+> type InP substrate 11 by selective chemical etching. An N<-> type InP buffer layer 12, the N<-> type In1-xGaxAs1-yPy light absorbing layer 13, the N type InP first multiplying layer 14, and the N<-> type InP second multiplying layer 15 are laminated on the entire surface including the concave part and epitaxially grown in the liquid pphase. By utilizing the effect that the thickness of the epitaxially grown layer at the concave part becomes thick, the thickness of the layer in the light receiving part, especially the first multiplying layer 14 with high carrier concentration on the light absorbing layer 13, is made larger than that around the surrounding part. The carrier concentration of the second multiplying layer 15 constituting the P-N junction is made low, and the guard ring effect is enhanced. Thus the low noise device is obtained. |
