AVALANCHE PHOTODIODE

• US 20140319638A1
• Filed: 10/19/2012
• Published: 10/30/2014
• Est. Priority Date: 10/20/2011
• Status: Active Grant

• Current Assignee: Agency For Science Technology and Research
• Original Assignee: Agency For Science Technology and Research
• Inventors: Chia, Ching Kean
• Granted Patent: US 9,041,136 B2
• Time in Patent Office: Days
• US Class Current: 257/438
• CPC Class Codes: H01L 31/107 the potential barrier working in avalanche mode, e.g. avalanche photodiodes
• CPC Class Codes: H01L 31/1075 in which the active layers, e.g. absorption or multiplication layers, form an heterostructure, e.g. SAM structure

Abstract

According to one aspect, there is provided an avalanche photodiode comprising a first semiconductor layer that absorbs photons of a first wavelength range and having a first energy bandgap; a second semiconductor layer that absorbs photons of a second wavelength range and having a second energy bandgap, the second energy bandgap being different from the first energy bandgap; and a control layer between the first semiconductor layer and the second semiconductor layer, the control layer having a third energy bandgap engineered to suppress carriers created from dark current.

Claims

1. An avalanche photodiode comprising

a first semiconductor layer that absorbs photons of a first wavelength range and having a first energy bandgap;

a second semiconductor layer that absorbs photons of a second wavelength range and having a second energy bandgap, the second energy bandgap being different from the first energy bandgap; and

a control layer between the first semiconductor layer and the second semiconductor layer, the control layer having a third energy bandgap engineered to suppress carriers created from dark current and to allow for a photocurrent with a substantially vertical profile near the breakdown voltage of the avalanche photodiode.

2. The avalanche photodiode of claim 1, wherein the substantially vertical photocurrent profile occurs around 1 to 2 volts before the breakdown voltage of the avalanche photodiode.

3. The avalanche photodiode of claim 1, the third energy bandgap being greater than either the first energy bandgap or the second energy bandgap.

4. The avalanche photodiode of claim 1, wherein the first semiconductor layer is a Ge photon absorption layer and the first wavelength range is from around 800 nm to around 1700 nm.

5. The avalanche photodiode of claim 4, wherein the second semiconductor layer is a GaAs photon absorption layer and the second wavelength range is from around 400 nm to around 870 nm.

6. The avalanche photodiode of claim 4, wherein the control layer is a Al_xGa_1-xAs layer, wherein x is a mole fraction between Al and Ga, where 0≦

x≦

1.

7. The avalanche photodiode of claim 6, wherein the Ge photon absorption layer is doped.

8. The avalanche photodiode of claim 7, wherein the GaAs photon absorption layer is undoped.

9. The avalanche photodiode of claim 7 wherein the GaAs photon absorption layer is doped with a polarity that is the same as the Ge photon absorption layer.

10. The avalanche photodiode of claim 7, wherein the Al_xGa_1-xAs layer is undoped.

11. The avalanche photodiode of claim 7, wherein the Al_xGa_1-xAs layer is doped with a polarity that is the same as the Ge photon absorption layer.

12. The avalanche photodiode of claim 7, wherein the Ge photon absorption layer is doped with a p-type dopant.

13. The avalanche photodiode of claim 1, wherein the combined thickness of the first semiconductor layer, the second semiconductor layer and the control layer is at least 600 nm.

14. The avalanche photodiode of claim 1, wherein the control layer acts as an interface between the first semiconductor layer and the second semiconductor layer, so that a first surface of the control layer is in contact with the first semiconductor layer and a second surface that is opposite to the first surface of the control layer is in contact with the second semiconductor layer.