WO2002099167A1

WO2002099167A1 - Crystalline compositions, radiation detector elements, and methods of formation

Info

Publication number: WO2002099167A1
Application number: PCT/US2001/017802
Authority: WO
Inventors: Howard L. Glass; James Patrick Flint
Original assignee: Honeywell International Inc.
Priority date: 2001-05-31
Filing date: 2001-05-31
Publication date: 2002-12-12

Abstract

A crystalline composition can include a crystal lattice containing Te and at least one of Cd and Zn at lattice points. The crystalline composition can also include a dopant provided at an average concentration inducing a resistivity of the crystalline composition greater than about 1 04 Ohm-centimeter. Also, the dopant may be p-type dopant and the crystalline composition can exhibit properties sufficient to detect radiation in at least one of a X-ray and a gamma ray portion of an electromagnetic spectrum. In particular, the dopant can be Sb. The dopant can compensate n-type native defects in the crystal lattice. Accordingly, a radiation detector element can contain Sb and at least two different additional chemical elements, for example, Te and at least one of Cd and Zn. One possible method of forming such a crystalline composition includes forming a crystal lattice from a starting charge containing Sb, perhaps at a concentration of about 5 ppma.

Description

Crystalline Compositions, Radiation Detector Elements, and Methods of Formation

TECHNICAL FIELD The present invention pertains to crystalline compositions, radiation detector elements, and methods of forming crystalline compositions or radiation detector elements.

BACKGROUND OF THE INVENTION Cadmium zinc telluride (CZT) is a well-known ternary compound semiconductor.

CZT is often considered a solid solution of binary compound semiconductors CdTe and ZnTe. CZT finds application in a variety of technologies. One such application is an electro-optical modulator for infrared optical systems, in particular, CO₂ lasers. CZT may also be useful as other optical elements such as lenses and Brewster windows. Further, CZT may find application as a room temperature nuclear radiation detector, especially for gamma rays and X-rays.

In each of the above-described CZT applications, a variety of doping methods have been attempted to produce doped CZT having desirable properties optimized for the particular application. In some cases, high resistivity CZT is desired, however, doping methods and dopants used currently often do not produce sufficiently high resistivity. In addition, conventional dopants and doping methods often produce the problem of dopants diffusing through the CZT of one of the above-described applications and forming or contributing to the formation of material defects, for example, inclusions or precipitates. Often, such defects are in the form of a second phase of material in a crystal lattice comprising the CZT. Accordingly, dopants and suitable doping methods for using such dopants are desired to provide increased resistivity while preventing the diffusion problems associated with present devices.

SUMMARY OF THE INVENTION

In one aspect of the invention, a crystalline composition includes a crystal lattice containing Te and at least one of Cd and Zn at lattice points and a p-type dopant at an average concentration inducing a resistivity of the crystalline composition greater than about 1x10⁴ Ohm-centimeter (Ohm-cm). By way of example, the crystalline composition can contain essentially a single crystal. Resistivity of the crystalline composition can be greater than about 1x10⁹ Ohm-cm. Further, a majority of the dopant can be comprisedi by the crystal lattice at Te substitutional positions. The dopant can be Sb. The average dopant concentration can be from about 10¹³ to about 10¹⁸ cm^"3.

In a further aspect of the invention, a crystalline composition can include a crystal lattice containing at least two different chemical elements at lattice points and a p-type dopant. The crystalline composition can exhibit properties sufficient to detect radiation in at least one of a X-ray and a gamma ray portion of an electromagnetic spectrum. As an example, the at least two different chemical elements can comprise Te and at least one of Cd and Zn. Also, a crystalline composition can include a crystal lattice containing Te and at least one of Cd and Zn at lattice points and a dopant comprising Sb. The lattice can exhibit the formula Cd_1-xZn_xTe, wherein x is from 0 to 1 , and an average dopant concentration from about 10¹³ to about 10¹⁸ cm^"3. In particular, the dopant concentration can be from about 10¹⁵ to about 10¹⁶ cm^"3.

In another aspect of the invention, a radiation detector element includes Sb and at least two different additional chemical elements. The at least two different additional chemical elements can include Te and at least one of Cd and Zn. The detector element may consist essentially of Te, Sb, and at least one of Cd and Zn. In a still further aspect, a crystalline composition forming method includes growing a crystal lattice containing at least two different chemical elements at lattice points and doping the crystal lattice with Sb. As an example, the at least two different chemical elements can include Te and at least one of Cd and Zn. N-type native defects can be formed in the crystal lattice. The doping can include compensating the n-type native defects. The doping can also include providing Sb in a starting charge used to grow the crystal lattice. The concentration of Sb in the starting charge can be from about 0.001 ppma (atomic parts per million) to about 100 ppma, in particular about 5 ppma.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below with reference to the following accompanying drawings.

Figure 1 shows a diagram of a radiation detection system according to an aspect of the present invention.

Figure 2 is a chart showing a current-voltage curve for a crystalline composition produced according to an aspect of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents. According to one aspect of the invention, a crystalline composition can contain a crystal lattice including Te and at least one of Cd and Zn. The Cd, Zn, and Te can exist at lattice points. Accordingly, the crystalline composition can consist essentially of a single crystal. Alternatively, only a portion of the crystalline composition may be a single crystal, even though other portions of the composition include Te and at least one of Cd and Zn. In applications where the crystalline composition is used as an electro-optical modulator, lenses, Brewster windows, and nuclear radiation detectors, the crystalline composition consisting essentially of a single crystal can be particularly advantageous. The crystal lattice of the crystalline composition can exhibit the formula Cd_1-xZn_xTe wherein x is from 0 to1. Accordingly, when x is 0 the crystal lattice exhibits the formula CdTe and when x is 1 the crystal lattice exhibits the formula ZnTe. In keeping with the formula described, cadmium zinc telluride (CZT) can exist over a range of compositions where the sum of Cd plus Zn atoms is approximately equal to the number of Te atoms. For example, x can be from about 0.015 to about 0.3 or, preferably, from about 0.05 to about 0.3. When using the crystalline composition as a detector element in a radiation detector, x is preferably about 0.1 , but can also be about 0.2. When using the crystalline composition for infrared optical systems, x is preferably about 0.035.

In the alternative, a crystalline composition according to the present aspect of the invention can contain a crystal lattice including at least two different chemical elements at lattice points. The at least two different chemical elements can include Te and at least one of Cd and Zn. However, the at least two different chemical elements can include other elements. Notably, complete or partial substitution of one or more of the three described chemical elements, such as substitution of Se for Te, might be made without substantially changing electrical and/or optical properties discussed herein. Still further, CZT can be provided over a range of deviations from the above- described ideal 1 :1 stoichiometry. Typically, non-stoichiometric CZT materials are referred to as Cd-rich or Te-rich. The non-stoichiometry is associated with equilibration between solid CZT and an ambient vapor and temperature during the process of growing a CZT crystal or during a subsequent high temperature process. The processing temperature, as well as the pressure and composition of the ambient vapor, will influence the extent of the equilibration between the ambient vapor and solid CZT.

Deviation from the ideal stoichiometry can produce second phase defects in the CZT. For example, under Te-rich conditions, Te inclusions or precipitates can be formed in the CZT. The second phase regions can act as defects by distorting the electric field in a radiation detection system or scattering optical beams in an electro- optical device. Further, the second phase regions can preferentially accumulate impurities or dopants leading to non-uniform distribution of dopants. Over time, or when exposed to elevated temperatures, the impurities or dopants may be released from the second phase regions to dynamically alter device properties.

CZT prepared under Te-rich conditions is typically found to be a p-type semiconductor. CZT prepared under Cd-rich conditions can be an n-type semiconductor. When prepared in the form of a single crystal, CZT is most often found to be p-type, corresponding to Te-rich conditions. One possible explanation for such circumstance is the existence of a native point defect in the p-type CZT caused by a Cd vacancy in the crystal lattice. Cd native point defects can form at least two electronic defect levels, corresponding to the two possible ionization states, -1 and -2. Additional defect levels can also exist due to formation of complexes of the native point defects with dopants or impurities. Accordingly, the electronic properties of CZT can be strongly influenced by native point defects, dopants, and impurities. In the context of this document, dopants and impurities are both considered atoms foreign to an intended composition. Impurities are foreign atoms introduced unintentionally while dopants are foreign atoms introduced intentionally or desirably existing in materials used to form the CZT. Regarding the native point defects, some such defects are caused by vacancies (missing atoms) as well as self-interstitials or anti-site defects (atoms at wrong locations) as known to those skilled in the art.

Since CZT can be prepared either as p-type or n-type, it is theoretically possible to find conditions under which the material is highly compensated and exhibits high resistivity. In practice, difficulty exists in obtaining sufficiently high resistivity without the use of doping. A dopant may be used that diffuses less than other typical dopants. In this manner, dynamic alteration of device properties can be minimized by minimizing the movements of dopants through the crystalline composition. According to another aspect of the invention, a dopant can exist in the crystalline composition at an average concentration sufficient to induce a resistivity of the crystalline composition greater than about 1x10⁴ Ohm-centimeter (Ohm-cm). For example, the average dopant concentration can be from about 10¹³ to about 10¹⁸ cm^"3, or preferably from about 10¹⁵ to about 10¹⁶ cm^"3. Preferably, resistivity can be greater than about 1x10⁶ Ohm-cm, greater than about 1x10⁸ Ohm-cm, or even greater than about 1x10⁹ Ohm-cm.

Conventionally, since most undoped CZT is p-type, those skilled in the art have concentrated on n-type dopants. Obtaining high resistivity CZT is thus attempted by compensating between native point defects and the dopant. A variety of n-type dopants have been evaluated and include, for example, Group III elements and Group VII elements. All of such dopants are relatively shallow dopants that will be active (ionized) at room temperature.

In keeping with the present aspects of the invention, it is possible to produce undoped CZT as an n-type semiconductor. Accordingly, the present invention provides the use of p-type dopants to achieve compensation and, therefore, high resistivity. Potential p-type dopants include Group IA elements and Group IB elements as well as Group VA elements. The Group IA and IB elements, such as Li, Na, Cu, or Ag are p- type when they substitute for Cd or Zn in a CZT crystal lattice. Dopants such as P, As, or Sb of Group VA are p-type dopants when substituting for Te in the crystal lattice.

Preferably, a crystalline composition according to the present invention includes at least one of a Group VA element, or more preferably, Sb. The Group IA and IB elements appear to incorporate into a crystalline composition both substitutionally at lattice points of a crystal lattice, as well as interstitially between lattice points. It is believed that such dopants exhibit n-type, rather than p-type, behavior at interstitial sites. Further, depending on the particular application, Group IA and Group IB elements can potentially exhibit unacceptably high diffusion rates. In addition to the diffusion phenomena discussed above, experience indicates that some p-type dopants might also be susceptible to diffusion to the surface of a crystalline composition. However, it is conceivable that such dopants might be acceptable in low temperature applications or applications where dynamic alteration of device properties is acceptable. Accordingly, Group VA elements are preferred. Elements P and As might be difficult to incorporate into CZT when high temperatures are used for crystal growth, however, lower temperature processes may be suitable. Element Sb is most preferred and believed suitable for incorporation at the high temperatures often used in CZT crystal growth. Due to the relatively large atomic radius and atomic weight of Sb, such element is also expected to be a stable dopant less susceptible to diffusion through a crystal lattice in comparison to dopants discussed above and otherwise known to those skilled in the art.

In conventional semiconductor fabrication, Sb can be a dopant considered for use to accomplish lower resistivity. Contrary to the conventional use of Sb, such dopant can be used according to the present aspects of the invention to establish a high resistivity material. A resistivity of 3.47x10¹⁰ Ohm-cm has been achieved and higher resistivities are conceivable. Accordingly, the present teaching of an Sb dopant in CZT yields surprising benefits.

One potential explanation for the advantages of Sb doping is the possibility that Sb substitutes for Te in the crystal lattice and/or fills Te vacancies that accompany Cd- rich processing conditions. Accordingly, one aspect of the inventions provides that at least some of a dopant, such as Sb as well as other dopants, is included by a crystal lattice at Te substitutional positions. Further, a majority of the Sb can be at Te substitutional positions. In this manner, the crystal lattice includes n-type native defects compensated by a p-type dopant. The average dopant concentration can be from about 10¹³ to about 10¹⁸ cm^"3, or preferably from about 10¹⁵ to about 10¹⁶ cm^"3.

A variety of scenarios exist within the knowledge of those skilled in the art attempting to achieve high resistivity through compensation. The scenarios are complex since they involve interactions among native point defects, impurities, dopants, and processing conditions for forming a crystalline composition. In the present aspects of the invention dopants are provided to produce higher resistivity than conventionally achieved. However, the present aspects of the invention provide additional advantages. In particular, the doping and processing conditions described herein achieve high resistivity without detracting from the physical and electronic properties of a crystalline composition that enable such composition to function well as a device, such as a nuclear radiation detector, electro-optical modulator, and other optical elements.

In nuclear radiation detectors, the present aspects of the invention achieve high resistivity without introducing excessive concentrations of recombination centers or traps that impede motion and detection of charges produced upon absorption of radiation, such as a gamma ray or X-ray photon. In a radiation detector, an applied electric field (voltage) depletes CZT of mobile electrical carriers. When a radiation photon is absorbed in the CZT, a large number of electron-hole pairs are generated. The electrons and holes move under the influence of the applied electric field, inducing charges on surface electrodes. Detection of the charges produces a signal that can be read using suitable electronics. Preferably, the charges produced by photon absorption are fully detected in a short period of time. The magnitude of the detected charge can be proportional to the energy of an absorbed photon so that the detector output provides a spectral analysis of radiation as well. Leakage current of the detector should also be low to avoid detection of a high background level of charge. Such requirements are met by a sufficiently high mobility and long lifetime of charges to provide rapid and complete detection and a sufficiently high resistivity to produce low leakage current at the applied voltage. Unfortunately, native point defects, impurities, dopants, and complexes of such components often form traps for charges in the CZT. Difficulty exists in evaluating what specific types of traps have a significant effect on performance of a radiation detector. For example, testing indicates that Te-antisite defects (Te in a Cd or Zn site) may be acceptable while a Cd vacancy defect at a -2 ionization state might not be acceptable. In addition, some dopants may cause polarization effects that produce drifts in detector performance over time. It is believed that at least Li, CI, and In dopants exhibit such drift.

Additionally, sufficient uniformity of properties throughout a crystalline composition promotes suitable performance of radiation detectors as well as electro- optical modulators and other optical elements.

In electro-optical modulators, the magnitude of the electro-optic effect is directly related to the applied electric field. Even though high resistivity CZT allows application of a large electric field, poor crystal quality can produce optical transmission losses. Transmission losses can produce heating in the optical element and damage or otherwise interfere with proper functioning of the device. A crystalline composition consisting essentially of a single crystal promotes the uniformity of properties. However, crystal quality can fluctuate. Preferably, the doping used to obtain desirable electronic properties can be compatible with a crystal growth process that yields high quality crystals. In particular, such process can avoid excessive formation of second phase precipitates or inclusions. As described further below, the present aspects of the invention provide CZT growth within a reasonably narrow range of Cd vapor pressures

, 5 corresponding to conditions that are less Te-rich or even somewhat Cd-rich compared to conditions used in conventional processes.

Figure 1 shows a radiation detection system 10 that includes a radiation detector 12. Radiation detector 12 further includes a detector element (not shown separately) comprising Sb and at least two different additional chemical elements. The at least two

10 different additional chemical elements can include Te, Sb, and at least one of Cd and Zn. A voltage source 16 applies an electric field across the detector element of radiation detector 12 during exposure of the detector element to radiation 18. Absorption of radiation 18 produces changes in the detector element of radiation detector 12, as described above and otherwise known to those skilled in the art, that may be sensed by

15 a charge detector 14. Charge detector 14 can provide output in any number of a variety of ways known to those skilled in the art enabling human readable indication of the existence of radiation.

The radiation detector element can consist essentially of Te, Sb, and at least one of Cd and Zn. Further, the detector element can include a single crystal exhibiting the

20 formula Cd_1-xZn_xTe, wherein x is from 0 to 1 , and an average Sb concentration of from about 10¹³ to about 10¹⁸ cm^"3. In keeping with descriptions of crystalline compositions provided above, a crystalline composition exhibiting properties sufficient to detect radiation in at least one of a X-ray and a gamma ray portion of an electromagnetic spectrum might be particularly suitable for the detector element of radiation detector 12

25 regardless of whether such composition includes Sb.

In a still further aspect of the invention, a crystalline composition forming method includes forming a crystal lattice comprising at least two different chemical elements, for example, Te and at least one of Cd and Zn, at lattice points. The method can further include forming n-type native defects in the crystal lattice and doping the crystal lattice with Sb. One example of doping the crystal lattice includes providing Sb in a starting charge used to grow the crystal lattice. The concentration of Sb in the starting charge can be from about 0.001 ppma (atomic parts per million) to about 100 ppma, or more preferably about 5 ppma.

A variety of crystal growth methods known to those skilled in the art exist and may be suitable for practicing the present invention in keeping with the aspects of such invention described above. One suitable method includes the Bridgman method, distinguished from the high pressure Bridgman method, yielding single crystal regions of large volume and high crystal quality characterized by a low incidence of second phase precipitates or inclusions. The method can employ a sealed quartz (fused silica) ampoule containing a starting charge within a pyrolytic boron nitride crucible. An example of such method is described in U.S. Patent 4,190,486 issued to Rudolph, et al. which is incorporated herein by reference for its. pertinent and supportive teachings. As modified in keeping with the present aspects of the invention, the ampoule can include a small excess of Cd in a range sufficient to minimize second phase regions. Sb may also be included in the ampoule as described above. Such a method is capable of producing doped CZT having total metallic impurities substantially less than 10¹⁶cm^"3. Often, doped CZT produced by such method can be free of cracks, voids, and pipes and exhibit a dislocation density of about 3x10⁴cm^"2. Dopant can be incorporated at lattice points. A single crystal volume from about 10 to about 20 cm² or larger in area with a thickness of from 1 to 3 or more cm can be obtained.

A preference for substituting into a Cd or Zn lattice site as opposed to a Te site can have a number of associated consequences. The extent to which a particular dopant is incorporated into CZT can depend on whether a Cd-rich or Te-rich scenario is provided. As discussed above, conventional processes provide a Te-rich scenario. A Cd-rich scenario, favoring formation of Te vacancies, may facilitate incorporation of dopants that prefer the Te site. If Te vacancies are present in significant concentrations, then the complexes formed with donors will be somewhat different for acceptor dopants at Te sites as opposed to dopants in conventional crystalline compositions that might be present at Cd or Zn sites.

Accordingly, Te substituted p-type dopants can form shallow acceptors that compensate deep donors. An advantage of using the deep donor compensation is that deep donor concentration can vary without significant impact on electrical properties. Suitable electrical properties can be achieved merely by a deep donor concentration exceeding a shallow acceptor concentration.

For the growth method described above, the relatively narrow range of Cd vapor pressure limits the concentration of Cd vacancies in the CZT. Further, the concentration of Te anti-site defects and other defects associated with Te-rich conditions can be minimized. A p-type dopant, such as Sb, can be included in starting materials to produce a sufficient concentration in the CZT to dominate over background impurities. Such a dopant thus can provide a controllable, net concentration of shallow acceptors compensated by deep donors. When providing a Cd vapor pressure, the deep donors are likely to be Cd interstitial atoms. The Cd vapor pressure can also be selected to foster incorporation of p-type dopant atoms by increasing the concentration of Te vacancies that can be preferred sites for such dopants, including Sb. In addition, the Cd vapor pressure can be adjusted during the growth process to insure a sufficient concentration of deep donors to compensate shallow acceptors. Such a compensation scenario can provide a sufficiently high resistivity to accomplish the aspects of the invention described herein without the need for further thermal treatment. However, additional thermal processing can be used according to the knowledge of those skilled in the art to further optimize electronic properties as desired. Notably, the deep donors described above can act as traps. However, the effect on device properties can be minimized by minimizing background impurity concentrations. The effect on device properties can also be minimized by using the minimum p-type dopant concentration consistent with the level of background impurities and adjusting the Cd vapor pressure during the growth process to avoid deep donor concentrations significantly higher than a minimum value suitable to achieve sufficiently high resistivity. Depending on the particular application for the CZT being produced, an optimum vapor pressure can be determined by analyzing device performance using CZT produced under a variety of trials. Cd vapor pressure can be adjusted by either selecting a particular quantity of excess Cd in a starting charge or, preferably, by controlling the temperature of a reservoir containing an excess of Cd. As a starting point, a Cd vapor pressure from about 0.8 to about 1.2 atmospheres may be suitable for obtaining a desired crystalline composition. Note should be taken that, in general, the relevant vapor pressure includes Zn in combination with Cd. Accordingly, consideration can be given that the excess provided includes both Cd and Zn as determined by equilibrium conditions for a particular composition of CZT.

EXAMPLE 1

Using the method described above, 2.5x10¹⁷ atoms of Sb/cm³ were provided in a starting charge of Cdo.gZn₀ iTe to produce a CZT single crystal. Electroless gold contacts were applied to the sample and the resistivity of the sample was calculated to be 3.47x10¹⁰ Ohm-cm from the current-voltage curve shown in Fig. 2 in the range of -0.5 volts to +0.5 volts. The resistivity was measured without any additional thermal processing after completion of the growth process.

Claims

1. A crystalline composition comprising: a crystal lattice comprising Te and at least one of Cd and Zn at lattice points; and a p-type dopant at an average concentration inducing a resistivity of the crystalline composition greater than about 1x10⁴ Ohm-centimeter (Ohm-cm).

2. The composition of claim 1 wherein the crystalline composition consists essentially of a single crystal.

3. The composition of claim 1 wherein a majority of the dopant is comprised by the crystal lattice at Te substitutional positions.

4. The composition of claim 1 wherein the crystal lattice comprises n-type native defects compensated by the p-type dopant.

5. The composition of claim 1 wherein the crystal lattice exhibits a formula of Cd_1-xZn_xTe wherein x is from 0 to 1.

6. The composition of claim 5 wherein x is from about 0.05 to about 0.3.

7. The composition of claim 1 wherein the resistivity of the crystalline composition is greater than about 1x10⁹ Ohm-cm.

8. The composition of claim 1 wherein the average dopant concentration is from about 10¹³ to about 10¹⁸ cm^"3.

9. The composition of claim 1 wherein the dopant comprises at least one of a Group VA element.

10. The composition of claim 1 wherein the dopant comprises Sb.

11. A crystalline composition comprising: a crystal lattice comprising at least two different chemical elements at lattice points; and a p-type dopant, the crystalline composition exhibiting properties sufficient to detect radiation in at least one of a X-ray and a gamma ray portion of an electromagnetic spectrum.

12. The crystalline composition of claim 11 wherein the at least two different chemical elements comprise Te and at least one of Cd and Zn.

13. The composition of claim 12 wherein a majority of the dopant is comprised by the crystal lattice at Te substitutional positions.

14. The composition of claim 11 wherein the crystal lattice comprises n-type native defects compensated by the p-type dopant.

15. The composition of claim 11 wherein the crystal lattice exhibits a formula of Cd_1-xZn_xTe wherein x is from 0 to 1.

16. The composition of claim 11 wherein an average dopant concentration is from about 10¹³ to about 10¹⁸ cm^"3.

17. The composition of claim 11 wherein the dopant comprises at least one of a Group VA element.

18. The composition of claim 11 wherein the dopant comprises Sb.

19. A crystalline composition comprising: a crystal lattice comprising Te and at least one of Cd and Zn at lattice points; and a dopant comprising Sb, the lattice exhibiting a formula of Cd_1-xZn_xTe, wherein x is from 0 to 1 , and an average dopant concentration of from about 10¹³ to about 10¹⁸ cm^"3.

20. The composition of claim 19 wherein a majority of the dopant is comprised by the crystal lattice at Te substitutional positions.

21. The composition of claim 19 wherein the crystal lattice comprises n-type native defects compensated by the Sb.

22. The composition of claim 19 wherein the dopant concentration is from about 10¹⁵ to about 10¹⁶ cm^"3.

23. A radiation detector element comprising Sb and at least two different additional chemical elements.

24. The detector element of claim 23 wherein the at least two different additional chemical elements comprise Te and at least one of Cd and Zn.

25. The detector element of claim 23 wherein the detector element consists essentially of Te, Sb, and at least one of Cd and Zn.

26. The detector element of claim 23 wherein the detector element comprises a single crystal exhibiting a formula of Cdι_-xZn_xTe, wherein x is from 0 to 1 , and an average Sb concentration of from about 10¹³ to about 10¹⁸ cm^"3.

27. The detector element of claim 26 wherein a majority of the Sb is comprised by the crystal at Te substitutional positions.

28. The detector element of claim 26 wherein the crystal comprises n-type native defects compensated by the Sb.

29. The detector element of claim 26 wherein the Sb concentration is from about 10¹⁵ to about 10¹⁶ cm^"3.

30. A crystalline composition forming method comprising: growing a crystal lattice comprising at least two different chemical elements at lattice points; forming n-type native defects in the crystal lattice; and doping the crystal lattice with Sb.

31. The method of claim 30 wherein the at least two different chemical elements comprise Te and at least one of Cd and Zn.

32. The method of claim 31 wherein the growing a crystal lattice is performed under Cd-rich conditions, forming the n-type native defects.

33. The method of claim 31 wherein a majority of the Sb is comprised by the crystal lattice at Te substitutional positions.

34. The method of claim 30 wherein the doping comprises compensating the n- type native defects.

35. The method of claim 30 wherein the crystal lattice exhibits a formula of Cd^ _xZn_xTe wherein x is from 0 to 1.

36. The method of claim 35 wherein x is from about 0.05 to about 0.3.

37. The method of claim 30 wherein an average Sb concentration is from about 10¹³ to about 10¹⁸ cm^"3.

38. The method of claim 37 wherein the Sb concentration is from about 10¹⁵ to about 10¹⁶ cm^"3.

39. The method of claim 30 wherein the doping comprises providing Sb in a starting charge used to grow the crystal lattice.

40. The method of claim 39 wherein a concentration of Sb in the starting charge about 0.001 ppma to about 100 ppma.

41. The method of claim 39 wherein a concentration of Sb in the starting charge t 5 ppma.

42. The crystalline composition formed by the method of claim 30.