Semiconductor Light Receiving Element Capacitance Reduction

The light absorbing layer is segmented into multiple thinner layers (first light absorbing layer and second light absorbing layer) with a buffer layer and oxidation layer inserted between them. This segmentation allows the total light absorption function to be distributed across multiple layers, reducing the capacitance of each individual layer while maintaining the overall light absorption efficiency, thereby reducing total capacitance without significantly increasing carrier travel time.

A buffer layer and oxidation layer are inserted as intermediary layers between the first and second light absorbing layers. The buffer layer provides electrical isolation and the oxidation layer (with lower dielectric constant) reduces capacitance between the light absorbing layers. These intermediary layers enable the light absorbing layer to be effectively divided without directly connecting the electrodes, thus reducing capacitance while minimizing impact on carrier travel time.

The light absorbing layer is divided into multiple segments (first and second light absorbing layers) separated by buffer and oxidation layers. This segmentation allows each segment to have optimized dimensions that balance light absorption area with capacitance reduction, enabling high photocurrent conversion efficiency while keeping total capacitance low.

Instead of increasing the in-plane area of the light absorbing layer to improve conversion efficiency, the patent introduces a vertical dimension by stacking multiple light absorbing layers with intervening buffer and oxidation layers. This vertical stacking allows the effective light absorption area to be increased through multiple layers while the capacitance between layers is reduced by the low-dielectric-constant oxidation layer, thus improving conversion efficiency without proportionally increasing capacitance.