Semiconductor device having an internal-field-guarded active region

Patent metadata

Field	Value
Publication number	US-10326048-B2
Application number	US-201815910386-A
Country	US
Kind code	B2
Filing date	Mar 2, 2018
Priority date	Mar 9, 2017
Publication date	Jun 18, 2019
Grant date	Jun 18, 2019

Abstract

A semiconductor device comprises a layer sequence formed by a plurality of polar single crystalline semiconductor material layers that each has a crystal axis pointing in a direction of crystalline polarity and a stacking direction of the layer sequence. A core layer sequence is formed by an active region made of an active layer stack or a plurality of repetitions of the active layer stack. The active layer stack has an active layer having a first material composition associated with a first band gap energy, and carrier-confinement layers embedding the active layer on at least two opposite sides thereof, having a second material composition associated with a second band gap energy larger than the first band gap energy. A pair of polarization guard layers is arranged adjacent to the active region and embedding the active region on opposite sides thereof.

First claim

What is claimed is:

1. A semiconductor device, comprising a layer sequence formed by a plurality of polar single crystalline semiconductor material layers that each have a crystal axis pointing in a direction that coincides with a direction of crystalline polarity and with a stacking direction of the layer sequence; wherein
the layer sequence is formed by a core layer sequence and shell layer sequences on opposite sides of the core layer sequence in the stacking direction; and wherein the core layer sequence is formed by
an active region made of an active layer stack or a plurality of repetitions of the active layer stack, the active layer stack being formed by an active layer having a first material composition that is associated with a first band gap energy, and by carrier-confinement layers embedding the active layer on at least two opposite sides thereof and having a second material composition that is associated with a second band gap energy larger than the first band gap energy, wherein the active layer and the carrier-confinement layers are configured to effect a quantum-confinement of charge carriers in the active layer in one, two or three spatial dimensions; and
a pair of polarization guard layers adjacent to the active region and embedding the active region on opposite sides thereof, wherein at least one of the polarization guard layers is formed by a semiconductor material layer having a third material composition that differs from the first and second material compositions and that is associated with a third band gap energy larger than the first band gap energy, but smaller than the second band gap energy.

2. The semiconductor device of claim 1 , wherein both polarization guard layers have the third material composition.

3. The semiconductor device of claim 1 , wherein only one of the polarization guard layers, herein called the first polarization guard layer, has the third material composition, and wherein the other of the polarization guard layers, herein called the second polarization guard layer, has the first material composition.

4. The semiconductor device of claim 3 , wherein the active layer and the first polarization or the active layer and the second polarization guard layer have an identical thickness.

5. The semiconductor device of claim 1 , wherein the first, second and third material compositions are selected so as to provide a band-gap energy of the at least one polarization guard layer that is larger than a transition energy associated with optical transitions of the quantum confined charge carriers in the active layer in operation of the semiconductor device.

6. The semiconductor device of claim 1 , wherein the second material composition and a thickness of the carrier-confinement layers are selected to allow a tunneling transport of the charge carriers between the polarization guard layers and the carrier-confinement layers under application of the operating voltage.

7. The semiconductor device of claim 1 , wherein the active layer has a thickness of less than 25 nanometer.

8. The semiconductor device of claim 1 , wherein a thickness of the polarization guard layers is at least one monolayer.

9. The semiconductor device of claim 1 , wherein a thickness of the polarization guard layer on at least one of the opposite sides of the active region is either smaller or at most equal to a thickness of the active layer.

10. The semiconductor device of claim 1 , wherein the shell layer sequences each comprise a respective outer layer, each outer layer forming one of two opposite end faces of the layer sequence, which end faces interface with a dielectric or a contact material of metallic electrical conductivity, and wherein each of the outer layers has the first material composition.

11. The semiconductor device of claim 8 , wherein the shell layer sequence comprises a first outer layer forming a top cover layer or second outer layer forming a bottom carrier layer of the layer sequence, the first or second outer layer having a thickness of at least 20 nanometer and having the first material composition.

12. The semiconductor device of claim 1 , wherein the layer sequence forms a sequence of epitaxial layers deposited on a carrier layer.

13. The semiconductor device of claim 1 , wherein the first material composition is GaN, the second material composition is AlN, and the third material composition is Al x Ga 1-x N, 1>x>0.

14. The semiconductor device of claim 13 , wherein the third material composition is Al x Ga 1-x N, with x smaller than or equal to 0.5.

15. The semiconductor device of claim 1 , wherein the layer sequence forms a diode and the active region comprises a layer stack configured to emit light under application of an operating voltage to the layer sequence, which operating voltage is suitable for allowing an electric current across the diode.

Assignees

• Univ Berlin Tech

Inventors

• Pahn Gerald
• Callsen Gordon
• Westerkamp Steffen

Classifications

• H01L33/16

  Electricity · mapped topic

• H01L33/20

  Electricity · mapped topic

• H01L2933/0083

  Electricity · mapped topic

• H01L33/007

  Electricity · mapped topic

• H01L33/04

  Electricity · mapped topic