JPS62128575A - Semiconductor photodetector - Google Patents

Abstract

PURPOSE:To form a Pin structure easily on a multilayer films on a semi- insulating substrate without shallow control of the depth direction of P-type diffusion by a method wherein P-type regions are formed on an N<-> type InGaAs layer successively and periodically with the space between adjacent P-type regions about the width of a depletion layer when a reverse voltage is applied. CONSTITUTION:An N<-> type InP layer 8 with an N-type carrier concentration of about 1X10<16>cm<-3>, an N<-> type InP layer 9 with a carrier concentration of about 1X10<15>cm<-3> and an N<-> type InGaAs layer 10 with a carrier concentration of also about 1X10<15>cm<-3> are formed on a semi-insulating substrate 7. Then a comb-shape P-type region 11 is formed by ion implantation of Zn and a P-type electrode Au/Zn 12 and an N-type electrode 13 are formed. The mutual space l between the comb teeth of the P-type region 11 is about the width of a depletion layer which is expanded when a reverse voltage is applied. As carriers induced by an incident light perform as a diffusion current in the P-type region 11 and as a drifting current in the depletion layer region 20, excess carriers induced near the surface perform as the drifting current so that the influence of the rate-determination by the diffusion current can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a semiconductor light receiving element having a structure suitable for optical integrated circuits and the like.

2. Description of the Related Art A conventional InGaAs/InP-based Pin-photodiode is shown in FIG. On the n-type InP substrate 1, n-1n
After forming a P layer 2 and an n-InGaAs layer 3 and performing mesa etching, a P type region 4 is formed by diffusion using a P type impurity such as L or ion implantation, and an electrode 5 is further formed. In the Pin photodiode, the device characteristics, especially the Doji efficiency, are greatly influenced by the controllability of the depth of the P-type head region.

Furthermore, the carriers generated during light reception behave as a diffusion current in the P-type head region and as a drift current in the depletion layer region, and the formation of the P-type region is one of the important issues in addition to element capacitance for high-speed operation. Become.

Problems to be Solved by the Invention When considering the application of the above-mentioned Pin photodiode to optical integrated circuits, etc., it is necessary to form it on a semi-insulating substrate.
At that time, there were problems such as controllability of the P-type region formation process and integration of the mesa structure. In addition, when trying to increase the speed by using two-dimensional electrons as carriers in a Peter junction, etc., the thickness of each layer becomes extremely thin, and the Pi
There were problems with controllability of n-structure formation, quantum efficiency, etc.

Means for Solving the Problems The present invention solves the problems by using nn-InC.
The P-type head region formed on the laA layer is formed as a continuous periodic region in which the interval between adjacent P-type regions is about the width of the depletion layer when a reverse voltage is applied, thereby forming a semiconductor light-receiving element. be.

Effect By using the above method, even when forming a pin structure on a multilayer thin film, it is possible to easily form a pin structure on a multilayer thin film on a semi-insulating substrate without requiring shallow control of the depth direction of P-type diffusion. In addition, the depletion layer spreads from continuous P-type head regions at intervals that extend to adjacent P-type head regions, and no electrodes are formed in periodic parts of the P-type head regions. Therefore, the quantum efficiency does not decrease, the influence of carrier diffusion current can be reduced, and since two-dimensional electrons at the heterojunction interface are used, high speed can be achieved.

Embodiment An embodiment of the present invention is shown in FIGS. 1a and 1b. InGaA
This will be explained using an s/InP light receiving element. Semi-insulating In
On the P substrate 7, there is an n-InP layer 8 with an n-type carrier concentration of about 1 x 10 cm and an n'' InP layer 9 with an n-type carrier concentration of about 1 x 1 cm. degree n-I
2000, 50, and 100 layers of nGaAs layer 1Q, respectively.
00 people each. Next, as shown in FIG. 1a, a comb-shaped P-type region 11 is formed by ion implantation to a depth of approximately 5OOQ8, as shown in FIG. An n-type electrode 13 is formed. The mutual spacing 1 between the P-type regions 11 is approximately the width of the depletion layer that expands when voltage is applied in the reverse direction. The light-receiving part includes a comb-shaped P-type region 11 and a depletion layer region 2 that expands when a reverse voltage is applied, which spreads between the comb-shaped P-type regions 11.
It is o.

Therefore, carriers generated by the incident light are transferred to the P-type region 1
1 as a diffusion current and in the depletion layer region 20 as a drift current, the more carriers generated near the surface behave as a drift current, reducing the rate-limiting influence of the diffusion current and increasing the speed.

As for electrons, high mobility can be achieved by the two-dimensional electron gas at the heterojunction, and semiconductors are fast, have high quantum efficiency, and are easy to integrate electrical devices using the two-dimensional electron gas at the heterojunction. A light receiving element is obtained.

Note that the P-type region 11 is not limited to a comb-like shape but may be a lattice-like shape.

Effects of the Invention As described above, according to the present invention, carriers generated by light reception on the surface are transferred to a depletion layer in the lateral Pin photodiode structure by forming a comb-shaped or lattice-shaped P-type head region. This method efficiently utilizes the absorption at the junction and reduces the diffusion current component, that is, the rate-determining component during high-speed operation, and also improves the mobility of electrons due to the two-dimensional electron gas in the heterojunction. According to the invention, therefore:
It is possible to obtain a planar light-receiving element suitable for integration on a semi-insulating substrate at high speed and with high efficiency.

[Brief explanation of drawings]

FIG. 1a is a plan view of a semiconductor photodetector according to an embodiment of the present invention, FIG. 1 is a sectional view taken along the line A-A' in FIG. be. 7...Semi-insulating InP substrate, 8...n
``'InP layer, 9... n-InP layer, 10...
...n-InGaAs layer, 11...P-type head area. Name of agent: Patent attorney Toshio Nakao and one other person
-Zn 1r)tn,),p'! 14 +L'+2-
．． 4u/l-So+j--%/Sh T 2nd Figure 1 --- n'l'fnP: 4; 1 2-0-t. 2 layers 3-, -ding n&a, As”4 +----/) Fu Island Gourd 5-Electric food

Claims (1)

[Claims] On a semi-insulating InP substrate, one conductivity type InP layer and an In_
xGa_1_-_xAs_yP_1_-_y layer (0≦x
≦1, 0≦y≦1), and the other conductivity type regions are periodically formed in a comb shape or a lattice shape on the surface of the one conductivity type In_xGa_1_-_xAs_yP_1_-_y layer,
A semiconductor light-receiving device characterized in that an interval between adjacent regions of the other conductivity type is approximately the width of a depletion layer when a reverse potential is applied.