USH848H - Method of passivating a substrate surface - Google Patents
Method of passivating a substrate surface Download PDFInfo
- Publication number
- USH848H USH848H US07/396,395 US39639589A USH848H US H848 H USH848 H US H848H US 39639589 A US39639589 A US 39639589A US H848 H USH848 H US H848H
- Authority
- US
- United States
- Prior art keywords
- layer
- passivating
- active layer
- substrate
- substrate surface
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000000758 substrate Substances 0.000 title claims abstract description 15
- 238000000034 method Methods 0.000 title claims description 15
- 239000000203 mixture Substances 0.000 claims abstract description 7
- 229910004613 CdTe Inorganic materials 0.000 claims description 5
- 238000001514 detection method Methods 0.000 claims description 4
- 238000001451 molecular beam epitaxy Methods 0.000 claims description 3
- 239000000956 alloy Substances 0.000 claims description 2
- 229910045601 alloy Inorganic materials 0.000 claims description 2
- 238000005229 chemical vapour deposition Methods 0.000 claims description 2
- 239000000969 carrier Substances 0.000 description 3
- 238000002161 passivation Methods 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007717 exclusion Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000006798 recombination Effects 0.000 description 1
- 238000005215 recombination Methods 0.000 description 1
- 238000003949 trap density measurement Methods 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H10F77/00—Constructional details of devices covered by this subclass
- H10F77/10—Semiconductor bodies
- H10F77/16—Material structures, e.g. crystalline structures, film structures or crystal plane orientations
- H10F77/169—Thin semiconductor films on metallic or insulating substrates
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H10F71/00—Manufacture or treatment of devices covered by this subclass
- H10F71/125—The active layers comprising only Group II-VI materials, e.g. CdS, ZnS or CdTe
- H10F71/1253—The active layers comprising only Group II-VI materials, e.g. CdS, ZnS or CdTe comprising at least three elements, e.g. HgCdTe
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H10F77/00—Constructional details of devices covered by this subclass
- H10F77/10—Semiconductor bodies
- H10F77/16—Material structures, e.g. crystalline structures, film structures or crystal plane orientations
- H10F77/169—Thin semiconductor films on metallic or insulating substrates
- H10F77/1696—Thin semiconductor films on metallic or insulating substrates the films including Group II-VI materials, e.g. CdTe or CdS
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
Definitions
- This invention relates in general to a method of passivation of a substrate surface, and in particular to the passivation of a substrate surface by the introduction of a thin layer of (Hg,Cd)Te, of increased Cd content, on the substrate surface before growth of the desired composition of (Hg,Cd)Te.
- the alloy family Hg 1-x Cd x Te has been used in infrared detection, the choice of the Cd fraction x allowing the choice of the infrared range. Both photoconductive and photovoltaic modes of detection have been used. Work has centered on growth by molecular beam epitaxy (MBE) and by metal-organic chemical vapor deposition (MOCVD). The compound has been grown on substrates of CdTe or lattice matched Cd 1-y Zn y Te. X-ray analysis however, has shown the existence of a damage layer presumably associated with lattice mismatch at the growth interface when CdTe is the substrate. Similar, but weaker, damage is expected on (Cd,Zn)Te substrates, because composition control in available material is poor.
- MBE molecular beam epitaxy
- MOCVD metal-organic chemical vapor deposition
- the general object of this invention is to provide a method of passivating a substrate surface.
- a more particular object of the invention is to provide a method of improving the efficiency of infrared devices by isolating the active layer from surface damage.
- the passivating layer can be thin and of about 500 to 1500 angstroms in thickness. However, the passivating layer must be thick enough to contain the damage layer.
- the doping of the passivating layer should be the same type as that of the active layer, so that photogenerated minority carriers are reflected from it.
- the composition of the passivating layer should be close to that of the active layer, to avoid a new source of mismatch, but sufficiently far different to provide effective exclusion of minority carriers from the damage layer.
- the passivating layer may be continuous with the active layer; a gradient in the Cd content, from high to low is expected to minimize damage in the active layer.
Landscapes
- Light Receiving Elements (AREA)
Abstract
The surface of a substrate is passivated by the introduction of a thin la of (Hg,Cd)Te, of increased Cd content, on the substrate surface before the growth of the desired composition of (Hg,Cd)Te.
Description
The Government has rights in this invention under Contract No. DAAB07-86-C-F069 with the Department of the Army.
This invention relates in general to a method of passivation of a substrate surface, and in particular to the passivation of a substrate surface by the introduction of a thin layer of (Hg,Cd)Te, of increased Cd content, on the substrate surface before growth of the desired composition of (Hg,Cd)Te.
The alloy family Hg1-x Cdx Te has been used in infrared detection, the choice of the Cd fraction x allowing the choice of the infrared range. Both photoconductive and photovoltaic modes of detection have been used. Work has centered on growth by molecular beam epitaxy (MBE) and by metal-organic chemical vapor deposition (MOCVD). The compound has been grown on substrates of CdTe or lattice matched Cd1-y Zny Te. X-ray analysis however, has shown the existence of a damage layer presumably associated with lattice mismatch at the growth interface when CdTe is the substrate. Similar, but weaker, damage is expected on (Cd,Zn)Te substrates, because composition control in available material is poor.
Recent studies have shown strong electrical activity near the growth interface of (Hg,Cd)Te grown by MBE on CdTe.
17 3 in Large donor and trap densities of greater than 1017 /cm3 in roughly 300 angstroms have been inferred. Such properties must cause rapid recombination of photo-generated carriers near the interface, and degrade infrared response.
The general object of this invention is to provide a method of passivating a substrate surface. A more particular object of the invention is to provide a method of improving the efficiency of infrared devices by isolating the active layer from surface damage.
It has now been found that the aforementioned objects can be attained by the introduction of a passivating layer or thin layer of (Hg,Cd)Te of increased Cd content, on the substrate surface before growth of the photo-active layer of the desired composition of (Hg,Cd)Te.
The passivating layer can be thin and of about 500 to 1500 angstroms in thickness. However, the passivating layer must be thick enough to contain the damage layer. The doping of the passivating layer should be the same type as that of the active layer, so that photogenerated minority carriers are reflected from it. The composition of the passivating layer should be close to that of the active layer, to avoid a new source of mismatch, but sufficiently far different to provide effective exclusion of minority carriers from the damage layer. For example, the Cd fraction for long wavelength detection is close to x=0.21. For operation at a temperature of 77° K, a composition of x=0.27 in the passivating layer is more than sufficient to cause electrical isolation of the active layer from the growth interface. Higher temperatures will require greater increases in the Cd content of the passivating layer over that of the active layer.
The passivating layer may be continuous with the active layer; a gradient in the Cd content, from high to low is expected to minimize damage in the active layer.
We wish it to be understood that we do not desire to be limited to the exact details of construction shown and described for obvious modifications will occur to a person skilled in the art.
Claims (10)
1. Method of passivating a substrate surface to be used for growth of a photo-active layer of the alloy family Hg1-x Cdx Te to be used in infrared detection, where choice of the Cd fraction x allows choice of infrared range, said method comprising growing a layer of relatively wide band gap (Hg,Cd)Te before growth of the photo-active layer.
2. Method according to claim 1 wherein the layers are grown by molecular beam epitaxy (MBE).
3. Method according to claim 1 wherein the layers are grown by metal-organic chemical vapor deposition (MOCVD).
4. Method according to claim 1 wherein the substrate is selected from the group consisting of CdTe and lattice matched Cd1-y Zny Te.
5. Method according to claim 4 wherein the substrate is CdTe.
6. Method according to claim 4 wherein the substrate is lattice matched Cd1-y Zny Te.
7. Method according to claim 1 wherein the passivating layer is about 500 to 1500 angstroms in thickness.
8. Method according to claim 1 wherein the doping of the passivating layer is the same type as that of the active layer.
9. Method according to claim 1 wherein the composition of the passivating layer should be close to that of the active layer.
10. Method according to claim 1 wherein the passivating layer is continuous with the active layer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/396,395 USH848H (en) | 1989-08-17 | 1989-08-17 | Method of passivating a substrate surface |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/396,395 USH848H (en) | 1989-08-17 | 1989-08-17 | Method of passivating a substrate surface |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| USH848H true USH848H (en) | 1990-11-06 |
Family
ID=23567028
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US07/396,395 Abandoned USH848H (en) | 1989-08-17 | 1989-08-17 | Method of passivating a substrate surface |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | USH848H (en) |
-
1989
- 1989-08-17 US US07/396,395 patent/USH848H/en not_active Abandoned
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| STCF | Information on status: patent grant |
Free format text: PATENTED CASE |