Semiconductor body

Abstract

A semiconductor body is disclosed. In an embodiment a semiconductor body includes an n-doped region comprising a first layer sequence comprising pairs of alternating layers, wherein a first layer and a second layer of each pair differ in their doping concentration, and wherein the first and second layers of each pair have the same material composition except for their doping and a second layer sequence comprising pairs of alternating layers, wherein a first layer and a second layer of each pair differ in their material composition, an active region, wherein the second layer sequence is disposed between the first layer sequence and the active region and a p-doped region, wherein the active region is disposed between the n-doped region and the p-doped region.

Claims

1. A semiconductor body comprising: an n-doped region comprising: a first layer sequence comprising pairs of alternating layers, wherein a first and a second layer of each pair differ in their doping concentration, and wherein the first and second layers of each pair have the same material composition except for their doping; and a second layer sequence comprising pairs of alternating layers, wherein a first layer and a second layer of each pair differ in their material composition; an active region, wherein the second layer sequence is disposed between the first layer sequence and the active region; and a p-doped region, wherein the active region is disposed between the n-doped region and the p-doped region.

2. The semiconductor body according to claim 1, wherein a number of pairs of the first layer sequence is at least three and at most five.

3. The semiconductor body according to claim 1, wherein the first layer of each pair of the first layer sequence is doped and the second layer of each pair of the first layer sequence is undoped.

4. The semiconductor body according to claim 1, wherein the n-doped region and the p-doped region are based on a nitride compound semiconductor material and the first layer sequence of the n-doped region is free of indium.

5. The semiconductor body in accordance with claim 1, wherein the active region is configured to generate or detect electromagnetic radiation.

6. The semiconductor body according to claim 1, further comprising an intermediate layer having a dopant concentration of at least 1*10.sup.18 1/cm.sup.3 between the first layer sequence and the second layer sequence.

7. The semiconductor body according to claim 6, wherein the intermediate layer is topographically flat.

8. The semiconductor body according to claim 1, wherein a layer thickness of the first layer of the first layer sequence is at least 1 nm and at most 30 nm, and wherein a layer thickness of the second layer of the first layer sequence is at least 30 nm and at most 100 nm.

9. The semiconductor body according to claim 1, wherein a number of pairs of the first layer sequence is at least 1 and at most 10.

10. The semiconductor body according to claim 1, wherein the first layer of the first layer sequence has a dopant concentration of at most 1*10.sup.18 1/cm.sup.3.

11. The semiconductor body according to claim 1, wherein a layer thickness of the second layer sequence is less than or equal to 50 nm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, the semiconductor bodies described here are explained in more detail in connection with an execution example and the corresponding figures.

(2) FIG. 1 shows a schematic cross-section through a semiconductor body.

(3) FIG. 2 shows a schematic cross-section through a semiconductor body according to an exemplary embodiment.

(4) FIG. 3 shows the failure rate due to electrostatic charge for two semiconductor bodies.

(5) FIG. 4 shows the dopant concentration of different layers of a semiconductor body.

(6) Same, similar or seemingly similar elements are provided in the figures with the same reference signs. The figures and the proportions of the elements depicted in the figures are not to be regarded as true to scale. Rather, individual elements may be exaggeratedly large for better representability and/or better comprehensibility.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(7) FIG. 1 shows a schematic cross-section through a semiconductor body 10. The semiconductor body 10 has an n-doped region 20. The n-doped region 20 may be located on a growth substrate or a carrier element. The n-doped region 20 has an n-contact layer 21. In a vertical direction z, an n-doped intermediate layer 22 is arranged on the n-contact layer 21. The n-doped intermediate layer 22 and the n-contact layer 21 may be formed by n-doped GaN.

(8) A second layer sequence 50 is arranged on the intermediate layer 22. The second layer sequence 50 consists of pairs of alternately arranged first and second layers 51, 52. In FIG. 1 only a representative first layer 51 and a representative second layer 52 of the second layer sequence 50 are shown. The second layer sequence 50 may comprise a plurality of alternating first and second layers 51, 52. The first layer 51 of the second layer sequence 50 can be formed with InGaN and the second layer 52 of the second layer sequence 50 with GaN. An active region 60 is arranged on the second layer sequence 50. A p-doped region 70 is arranged on the active region 60.

(9) In the semiconductor body 10, which is shown in FIG. 1, the second layer sequence 50 prevents diffusion of dopants and other foreign atoms into the active region 60 and therefore the semiconductor body 10 can be operated more efficiently.

(10) FIG. 2 shows a schematic cross-section through a semiconductor body 10 according to an exemplary embodiment. The semiconductor body 10 has an n-doped region 20 and a p-doped region 70. The n-doped region 20 has an n-contact layer 21.

(11) In the vertical direction z, a first layer sequence 30 is arranged on the n-contact layer 21. The first layer sequence 30 comprises pairs of alternating first layers 31 and second layers 32. Therein the first layers 31 are n-doped with silicon and the second layers 32 are nominally undoped. This means that the second layers 32 are not intentionally doped, but it can happen that dopants from the first layers 31 diffuse into the second layers 32. The first layers 31 of the first layer sequence 30 have a maximum dopant concentration of 1*10.sup.18 1/cm.sup.3. The first and second layers 31, 32 of each pair thus differ in their doping concentration and have the same material composition except for their doping. The n-contact layer 21 and the first layer sequence 30 can be formed with GaN. In this example, the first layer sequence 30 comprises three pairs of first and second layers 31, 32.

(12) In the vertical direction z, an intermediate layer 40 is arranged on the first layer sequence 30. The intermediate layer 40 can be formed with GaN and n-doped with silicon with a dopant concentration of at least 1*10.sup.18 per cm.sup.3. Due to the high dopant concentration of the intermediate layer 40, an active region 60 can be grown with improved quality and the stability of the semiconductor body against electrostatic discharge is increased.

(13) A second layer sequence 50 is arranged on the intermediate layer 40. The second layer sequence 50 comprises pairs of alternately arranged first layers 51 and second layers 52. The first layers 51 of the second layer sequence 50 can be formed with InGaN and the second layers 52 of the second layer sequence 50 can be formed with GaN. The first and second layers 51, 52 of each pair thus differ in their material composition. In FIG. 2 only a representative first layer 51 and a representative second layer 52 of the second layer sequence 50 are shown. The second layer sequence 50 may comprise a plurality of alternating first and second layers 51, 52. The layer thickness of the second layer sequence 50 is less than or equal to 50 nm.

(14) The active region 60 is applied to the second layer sequence 50. The second layer sequence 50 is thus arranged between the first layer sequence 30 and the active region 60. For example, the active region 60 may comprise a multiple quantum well structure comprising a plurality of alternating quantum well layers and barrier layers. The barrier layers can be formed with GaAlN or GaN and the quantum well layers can be formed with InAlGaN or InGaN. The p-doped region 70 is arranged on the active region 60. The active region 60 is thus arranged between the n-doped and the p-doped region 20, 70.

(15) By introducing the first layer sequence 30 into the semiconductor body 10, the stability against electrostatic discharge of the semiconductor body 10 can be increased. By introducing the second layer sequence 50 into the semiconductor body 10, the semiconductor body 10 can be operated more efficiently, since the diffusion of dopants and other impurities into the active region 60 is prevented or reduced by the second layer sequence 50.

(16) FIG. 3 shows the electrostatic charge failure rate for the semiconductor body 10 shown in FIG. 1 and the semiconductor body 10 shown in FIG. 2. The failure rate in the 2 kV HBM (human body model)-test, i.e., at a discharge of 2 kV, is plotted on the y-axis. On the x-axis, the failure rate for the semiconductor body 10 shown in FIG. 1 is shown on the left and the failure rate for the semiconductor body 10 shown in FIG. 2 is shown on the right. For the semiconductor body 10 in FIG. 1, the failure rate is about 90 percent. In contrast, the failure rate for the semiconductor body 10 in FIG. 2 is less than 10 percent. A difference between the semiconductor bodies 10 in FIGS. 1 and 2 is that the semiconductor body 10 in FIG. 2 has the first layer sequence 30 in addition to the second layer sequence 50. By introducing the first layer sequence 30, the failure rate during electrostatic discharge can thus be surprisingly significantly reduced.

(17) FIG. 4 shows the dopant concentration of different layers of a sample semiconductor body 10 as shown in FIG. 2. The dopant concentration was determined by secondary ion mass spectroscopy. On the y-axis the dopant concentration in per cm.sup.3 is plotted and on the x-axis the depth from which the secondary ions are detected is plotted in nm. A depth of 0 nm corresponds to the surface of the semiconductor body 10. The peak around 250 nm refers to the intermediate layer 40. Said intermediate layer has a dopant concentration of about 1*10.sup.19 1/cm.sup.3. Between about 290 nm and 430 nm depth, the first layer sequence 30 is located. Due to the small layer thicknesses of the first and second layers 31, 32 of the first layer sequence 30, these cannot be assigned in the spectrum. It can be seen that the first layer sequence 30 has a lower dopant concentration than the intermediate layer 40.

(18) The invention is not limited by the description using the exemplary embodiments to these. Rather, the invention includes any new feature and any combination of features, which in particular includes any combination of features in the patent claims, even if that feature or combination itself is not explicitly mentioned in the patent claims or execution examples.