Showing papers on "Diode published in 1999"
TL;DR: Improved materials would not only help to cool advanced electronics but could also provide energy benefits in refrigeration and when using waste heat to generate electrical power.
Abstract: In a typical thermoelectric device, a junction is formed from two different conducting materials, one containing positive charge carriers (holes) and the other negative charge carriers (electrons). When an electric current is passed in the appropriate direction through the junction, both types of charge carriers move away from the junction and convey heat away, thus cooling the junction. Similarly, a heat source at the junction causes carriers to flow away from the junction, making an electrical generator. Such devices have the advantage of containing no moving parts, but low efficiencies have limited their use to specialty applications, such as cooling laser diodes. The principles of thermoelectric devices are reviewed and strategies for increasing the efficiency of novel materials are explored. Improved materials would not only help to cool advanced electronics but could also provide energy benefits in refrigeration and when using waste heat to generate electrical power.
2,808 citations
TL;DR: The role of extended and point defects, and key impurities such as C, O, and H, on the electrical and optical properties of GaN is reviewed in this article, along with the influence of process-induced or grown-in defects and impurities on the device physics.
Abstract: The role of extended and point defects, and key impurities such as C, O, and H, on the electrical and optical properties of GaN is reviewed. Recent progress in the development of high reliability contacts, thermal processing, dry and wet etching techniques, implantation doping and isolation, and gate insulator technology is detailed. Finally, the performance of GaN-based electronic and photonic devices such as field effect transistors, UV detectors, laser diodes, and light-emitting diodes is covered, along with the influence of process-induced or grown-in defects and impurities on the device physics.
1,693 citations
TL;DR: In this article, the magnetic semiconductor BexMnyZn1-x-ySe is used as a spin aligner to inject spin-polarized charge into a non-magnetic semiconductor device.
Abstract: The field of magnetoelectronics has been growing in practical importance in recent years1 For example, devices that harness electronic spin—such as giant-magnetoresistive sensors and magnetoresistive memory cells—are now appearing on the market2 In contrast, magnetoelectronic devices based on spin-polarized transport in semiconductors are at a much earlier stage of development, largely because of the lack of an efficient means of injecting spin-polarized charge Much work has focused on the use of ferromagnetic metallic contacts3,4, but it has proved exceedingly difficult to demonstrate polarized spin injection More recently, two groups5,6 have reported successful spin injection from an NiFe contact, but the observed effects of the spin-polarized transport were quite small (resistance changes of less than 1%) Here we describe a different approach, in which the magnetic semiconductor BexMnyZn1-x-ySe is used as a spin aligner We achieve injection efficiencies of 90% spin-polarized current into a non-magnetic semiconductor device The device used in this case is a GaAs/AlGaAs light-emitting diode, and spin polarization is confirmed by the circular polarization state of the emitted light
1,650 citations
TL;DR: In this article, a truncated-inverted-pyramid (TIP) chip geometry was proposed to decrease the mean photon path length within the crystal, and thus reduce the effects of internal loss mechanisms.
Abstract: A truncated-inverted-pyramid (TIP) chip geometry provides substantial improvement in light extraction efficiency over conventional AlGaInP/GaP chips of the same active junction area (∼0.25 mm2). The TIP geometry decreases the mean photon path-length within the crystal, and thus reduces the effects of internal loss mechanisms. By combining this improved device geometry with high-efficiency multiwell active layers, record-level performance for visible-spectrum light-emitting diodes is achieved. Peak efficiencies exceeding 100 lm/W are demonstrated (100 mA dc, 300 K) for orange-emitting (λp∼610 nm) devices, with a peak luminous flux of 60 lumens (350 mA dc, 300 K). In the red wavelength regime (λp∼650 nm), peak external quantum efficiencies of 55% and 60.9% are measured under direct current and pulsed operation, respectively (100 mA, 300 K).
511 citations
Patent•
29 Mar 1999TL;DR: In this article, a molecular wire crossbar memory (MWCM) system is provided. The MWCM comprises a two-dimensional array of a plurality of nanometer-scale devices, each device comprising a junction formed by a pair of crossed wires where one wire crosses another and at least one connector species connecting the pair of wires in the junction.
Abstract: A molecular wire crossbar memory (MWCM) system is provided. The MWCM comprises a two-dimensional array of a plurality of nanometer-scale devices, each device comprising a junction formed by a pair of crossed wires where one wire crosses another and at least one connector species connecting the pair of crossed wires in the junction. The connector species comprises a bi-stable molecular switch. The junction forms either a resistor or a diode or an asymmetric non-linear resistor. The junction has a state that is capable of being altered by application of a first voltage and sensed by application of a second, non-destructive voltage.
504 citations
TL;DR: In this paper, the lowest room-temperature threshold current density, 26 A/cm/sup 2 ), of any semiconductor diode laser was reported for a quantum dot device with a single InAs dot layer contained within a strained In/sub 0.85/As quantum well.
Abstract: The lowest room-temperature threshold current density, 26 A/cm/sup 2/, of any semiconductor diode lasers is reported for a quantum dot device with a single InAs dot layer contained within a strained In/sub 0.15/Ga/sub 0.85/As quantum well. The lasers are epitaxially grown on a GaAs substrate, and the emission wavelength is 1.25 /spl mu/m.
469 citations
TL;DR: In this paper, the authors describe the design, fabrication, and measured characteristics of the high-power optically pumped-semiconductor (OPS) vertical-external-cavity surface-emitting lasers (VCSELs).
Abstract: We describe the design, fabrication, and measured characteristics of the high-power optically pumped-semiconductor (OPS) vertical-external-cavity surface-emitting lasers (VCSELs). Using diode laser pumping, we have recently demonstrated operation of such lasers, which for the first time generate high (watt-level) power and a circular Gaussian beam directly from a semiconductor laser. These OPS-VECSELs have a strain-compensated multi-quantum-well InGaAs-GaAsP-GaAs structure and operate CW near /spl lambda//spl sim/1004 nm with output power of 0.69 W in TEM/sub 11/ mode, 0.52 W in TEM/sub 00/ mode and 0.37 W coupled to a single-mode fiber. With multiple pump and gain elements, OPS-VCSEL technology is scalable to the multiwatt power levels. Such lasers will prove useful in a variety of applications requiring compact and efficient sources with high-power output in a single-mode fiber or with diffraction-limited beam quality.
389 citations
Patent•
15 Dec 1999TL;DR: In this paper, transistors and diodes are manufactured by ink-jet printing using a transfer member, and these electronic devices are used in addressing an electronic display, such as a display.
Abstract: Electronic devices such as transistors and diodes are manufactured by ink-jet printing using a transfer member. These electronic devices are used in addressing an electronic display.
341 citations
TL;DR: In this paper, solar-blind ultraviolet photodiodes with a band-edge wavelength of 285 nm were fabricated on laterally epitaxially overgrown GaN grown by metalorganic chemical vapor deposition.
Abstract: Solar-blind ultraviolet photodiodes with a band-edge wavelength of 285 nm were fabricated on laterally epitaxially overgrown GaN grown by metalorganic chemical vapor deposition. Current–voltage measurements of the diodes exhibited dark current densities as low as 10 nA/cm2 at −5 V. Spectral response measurements revealed peak responsivities of up to 0.05 A/W. Response times for these diodes were measured to be as low as 4.5 ns for 90%-to-10% fall time. For comparison, diodes were fabricated using the same p–i–n structure deposited on dislocated GaN. These diodes had dark current densities many orders of magnitude higher, as well as a less sharp cutoff, and a significant slow tail under impulse excitation.
319 citations
TL;DR: InGaN multi-quantum-well structure laser diodes formed on the GaN layer above the SiO2 mask area can have a lifetime of more than 10,000 hours and the localized energy states caused by In composition fluctuation in the In GaN active layer are related to the high efficiency of the InGaN-based emitting devices.
280 citations
TL;DR: In this article, the optical characteristics of the first laser diodes fabricated from a single-InAs quantum-dot layer placed inside a strained InGaAs QW are described, and the saturated modal gain for this novel laser active region is found to be 9-10 cm/sup -1/ in the ground state.
Abstract: The optical characteristics of the first laser diodes fabricated from a single-InAs quantum-dot layer placed inside a strained InGaAs QW are described. The saturated modal gain for this novel laser active region is found to be 9-10 cm/sup -1/ in the ground state. Room temperature threshold current densities as low as 83 A/cm/sup 2/ for uncoated 1.24-/spl mu/m devices are measured, and operating wavelengths over a 190-nm span are demonstrated.
Patent•
11 Aug 1999TL;DR: In this article, a diode is formed in a container in an insulative structure layered on a substrate of an integrated circuit, and the container is then partially filled with a polysilicon material, by methods such as conformal deposition, leaving a generally vertical seam in the middle of the material.
Abstract: A method for manufacturing a diode having a relatively improved on-off ratio. The diode is formed in a container in an insulative structure layered on a substrate of an integrated circuit. The container is then partially filled with a polysilicon material, by methods such as conformal deposition, leaving a generally vertical seam in the middle of the polysilicon material. An insulative material is deposited in the seam. The polysilicon material is appropriately doped and electrical contacts and conductors are added as required. The diode can be coupled to a chalcogenide resistive element to create a chalcogenide memory cell.
TL;DR: In this paper, a long-lifetime violet InGaN multi-quantum-well/GaN/AlGaN separate-confinement heterostructure laser diodes (LDs) were successfully fabricated using epitaxially laterally overgrown GaN by reducing a large number of threading dislocations originating from the interface between GaN and sapphire substrate.
Abstract: High-efficiency light-emitting diodes emitting amber, green, blue and ultraviolet light have been obtained through the use of InGaN active layers instead of GaN active layers. The localized energy states caused by In composition fluctuation in the InGaN active layer seem to be related to the high efficiency of the InGaN-based emitting devices. Long-lifetime violet InGaN multi-quantum-well/GaN/AlGaN separate-confinement heterostructure laser diodes (LDs) were successfully fabricated using epitaxially laterally overgrown GaN by reducing a large number of threading dislocations originating from the interface between GaN and sapphire substrate. The threading dislocations shorten the lifetime of the LDs through an increase of the threshold current density. The LDs with cleaved mirror facets showed an output power as high as 30 mW under room-temperature continuous-wave (CW) operation with a stable fundamental transverse mode. The lifetime of the LDs at a constant output power of 5 mW was estimated to be approximately 3000 h under CW operation at an ambient temperature of 50 °C. These results indicate that these LDs already can be used for many real applications, such as digital versatile disks, laser printers, sensors and exciting light sources as a commercial product with a high output power and a high reliability.
TL;DR: In this article, the present status of the rapidly developing field of semiconductor laser diodes based on self-organized quantum dots (QDs) is reviewed, and three applications of large commercial interest are discussed in detail: 1300nm QD laser on GaAs substrate, QD surface emitting lasers, and high power QD lasers.
Abstract: We review the present status of the rapidly developing field of semiconductor laser diodes based on self-organized quantum dots (QDs). Several milestones have been achieved since the first realization of such a device in 1994: above room-temperature cw operation, the lowest threshold current density of any semiconductor laser diode, high temperature stability, an extended wavelength range on GaAs substrate and high power operation. After a brief introduction we discuss the tremendous advances in epitaxial growth, device performance, and theoretical understanding of QD lasers. Three applications of large commercial interest are discussed in detail: 1300 nm QD lasers on GaAs substrate, QD surface emitting lasers, and high power QD lasers. Finally, we give an outlook on future developments.
Book•
01 Jan 1999
TL;DR: In this paper, the authors present a detailed overview of Optoelectronic pn-Junction devices and their application in the field of device fabrication and packaging, and their reliability.
Abstract: Basics of Optoelectronic pn-Junction Devices. Light-Emitting Diodes. Laser Diodes. Photodiodes. Optical Modulators. Device Fabrication and Packaging. Reliability. Application of Optoelectronic pn-Junction Devices. Index.
TL;DR: In this paper, 1 kV 4H and 6 h SiC Schottky diodes utilizing a metal-oxide overlap structure for electric field termination were fabricated using Ni-SiC ohmic contact formation.
Abstract: We have fabricated 1 kV 4H and 6H SiC Schottky diodes utilizing a metal-oxide overlap structure for electric field termination. This simple structure when used with a high barrier height metal such as Ni has consistently given us good yield of Schottky diodes with breakdown voltages in excess of 60% of the theoretically calculated value. This paper presents the design considerations, the fabrication procedure, and characterization results for these 1 kV Ni-SiC Schottky diodes. Comparison to similarly fabricated Pt-SiC Schottky diodes is reported. The Ni-SiC ohmic contact formation has been studied using Auger electron spectroscopy and X-ray diffraction. The characterization study includes measurements of current-voltage (I-V) temperature and capacitance-voltage (C-V) temperature characteristics. The high-temperature performance of these diodes has also been investigated. The diodes show good rectifying behavior with ON/OFF current ratios, ranging from 10/sup 6/ to 10 at 27/spl deg/C and in excess of 10/sup 6/ up to 300/spl deg/C.
TL;DR: In this paper, the effects of surface defects on performance of kV-class 4H- and 6H-SiC epitaxial p-n junction diodes were investigated.
Abstract: Effects of surface defects on performance of kV-class 4H- and 6H-SiC epitaxial p-n junction diodes were investigated. The perimeter recombination and generation, instead of the bulk process, are responsible for forward recombination current and reverse leakage current of the diodes, respectively. Mapping studies of surface morphological defects have revealed that triangular-shaped defects severely degrade high-blocking capability of the diodes whereas shallow round pits and scratch give no direct impact. Device-killing defects in SiC epilayers are discussed based on breakdown voltage mapping. Effective minority carrier lifetimes are mainly limited not by bulk recombination but by perimeter recombination.
TL;DR: In this article, a transparent polycrystalline p-n heterojunctions on a glass substrate were fabricated and the structure of the diode was n+-ZnO electrode/n- ZnO/p-SrCu2O2/In2−xSnxO3 electrode on the substrate.
Abstract: All oxide-based, transparent polycrystalline p–n heterojunctions on a glass substrate were fabricated. The structure of the diode was n+-ZnO electrode/n-ZnO/p-SrCu2O2/In2−xSnxO3 electrode on the substrate. The contact between the n- and p-type semiconducting oxides was found to be rectifying. The ratio of forward current to the reverse current exceeded 80 within the range of applied voltages of −1.5 to +1.5 V and the estimated diode factor (n value) was 1.62. The diode structure was fabricated on a glass plate with the total thickness of 1.3 μm and possessed an optical transmission of 70%–80% in the visible region.
TL;DR: In this article, the characteristics of Pt Schottky diodes on n-type GaN in hydrogen and propane are reported for the first time, and they are able to detect hydrogen from 200-400°C.
Abstract: The characteristics of Pt Schottky diodes on n-type GaN in hydrogen and propane are reported for the first time. This response from 200–400°C has been characterized by current–voltage measurements, revealing that the diodes are able to detect hydrogen from 200–400°C and propane from 300–400°C. The high temperature stability of Pt diodes on GaN has been investigated by long term annealing at 400°C in Ar or 20% O2 in Ar. The diodes have been held at 400°C for 500 h without degradation of their electrical characteristics or response to hydrogen-containing gases.
TL;DR: In this article, an empirical closed-form expression is presented to predict the avalanche breakdown voltage of wide band-gap semiconductors based on an approximation of the impact ionization coefficient in terms of the seventh power of the electric field.
Abstract: Applicability of GaN in unipolar and bipolar devices for high-power electronic applications is evaluated with respect to similar devices based on other materials. Specific resistance is used as a measure of unipolar performance. In order to evaluate bipolar performance, 700 and 6000 V p-i-n diodes based on Si, 6H-SiC, and GaN are compared with respect to forward conduction and reverse recovery performance at room temperature and high-temperature conditions. It is shown that GaN is advantageous not only for high voltage unipolar applications, but also for bipolar applications. An empirical closed-form expression is presented to predict the avalanche breakdown voltage of wide band-gap semiconductors. Formulation of the expression is based on an approximation of the impact ionization coefficient in terms of seventh power of the electric field.
TL;DR: In this article, a bipolar transport/emitting layer is proposed and implemented for making organic light-emitting diodes, and a significant improvement in device lifetime is attributed to the elimination of the heterointerface present in the conventional devices.
Abstract: A structure based on a bipolar transport/emitting layer is proposed and implemented for making organic light-emitting diodes. Compared to the conventional heterojunction organic light-emitting diodes, more than a factor of six improvement in device reliability (a projected operating lifetime of 70 000 h) is achieved in the structure. The significant improvement in device lifetime is attributed to the elimination of the heterointerface present in the conventional devices which greatly affects the device reliability.
TL;DR: In this article, an organic light-emitting diodes have been fabricated using erbium tris(8-hydroxyquinoline) as the emitting layer and N, N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphensyl-4,4′-Diamine as the hole-transporting layer.
Abstract: Organic light-emitting diodes have been fabricated using erbium tris(8-hydroxyquinoline) as the emitting layer and N, N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine as the hole-transporting layer. Room-temperature electroluminescence was observed at 1.54 μm due to intra-atomic transitions between the 4I13/2 and 4I15/2 levels in the Er3+ ion. These results suggest a possible route to producing a silicon-compatible 1.54 μm source technology.
TL;DR: In this article, a combination of light scattering at a textured top surface and reflection on a backside mirror was proposed to achieve 22% external quantum efficiency of nonresonant cavity (NRC) light-emitting diodes.
Abstract: The external quantum efficiency of light-emitting diodes (LEDs) is usually limited by total internal reflection at the semiconductor–air interface. This problem can be overcome by a combination of light scattering at a textured top surface and reflection on a backside mirror. With this design, we achieve 22% external quantum efficiency. One of the main loss mechanisms in such nonresonant cavity (NRC) light-emitting diodes is coupling into an internal waveguide. Texturing the surface of this waveguide allows the partial extraction of the confined light. In this way, we demonstrate an increase in the external quantum efficiency of NRC-LEDs to 31%.
TL;DR: In this paper, variable-temperature Hall-effect measurements were employed to optimize doping for GaN layers utilized in blue, blue-green and green light emitting diodes (LEDs).
Abstract: Variable-temperature Hall-effect measurements were employed to optimize doping for GaN layers utilized in blue, blue-green and green light emitting diodes (LEDs). N-type doping was accomplished by doping with Si, Ge, and O, and the electronic properties of these donors were studied. Si and Ge, which substitute for Ga, are shallow donors with almost identical activation energies for ionization (ca. 17 and ca. 19 meV, respectively, for a donor concentration of ca. 3×10 17 cm −3 ). O substitutes for N and introduces a slightly deeper donor level into the bandgap of GaN having an activation energy of ca. 29 meV (for a donor concentration of ca. 1×10 18 cm −3 ). Mg doping was employed to achieve p-type conductivity for GaN device layers. Mg substitutes for Ga introducing a relatively deep acceptor level. For the analysis of the variable-temperature Hall-effect data, it was found important to take the coulomb interaction between ionized acceptors into account, leading to lower activation energy with increasing degree of ionization (increasing temperature). The activation energy for ionization of Mg acceptors in GaN was thus estimated to be (208±6) meV for very low acceptor concentrations. Using optimized nitride layers, LEDs with typical external quantum efficiencies of ca. 10% in the blue and blue-green, and ca. 8% in the green wavelength range were achieved. Due to optimized doping, the forward voltages for these diodes were as low as 3.2 V at 20 mA drive current.
TL;DR: An experimental demonstration of optical synchronization of chaotic external-cavity semiconductor laser diodes is reported for what is believed to be the first time.
Abstract: An experimental demonstration of optical synchronization of chaotic external-cavity semiconductor laser diodes is reported for what is believed to be the first time. It is shown that at an optimum coupling strength between the master and the slave lasers high-quality synchronization can be obtained.
TL;DR: Two new detectors designed specifically for use in small stereotactic fields were compared against similar, more routine, detectors, finding no single detector was found to be ideal and neither of the two new measurement devices had any significant advantages over more routine devices, in the situations measured.
Abstract: Two new detectors (0.015 cm3 ion chamber from PTW, 0.6 mm diameter diode from Scanditronix AB) designed specifically for use in small stereotactic fields were compared against similar, more routine, detectors (0.125 cm3 ion chamber, parallel plate chamber, shielded and unshielded diodes and film). Percentage depth doses, tissue maximum ratios, off-axis ratios and relative output factors were compared for circular fields in the 40-12.5 mm diameter range, with a view to identifying the optimum detector for stereotactic beam data acquisition. Practical suggestions for beam data collection and analysis are made, with an emphasis on what is achievable practically in radiotherapy departments where the primary demand is to provide a routine service. No single detector was found to be ideal, and neither of the two new measurement devices had any significant advantages over more routine devices, in the situations measured. Although the new 0.015 cm3 ion chamber was an improvement on a 0.125 cm3 ion chamber in the measurement of profiles, it was still too large when compared with a diode. The new small diode had a low signal to noise ratio which made reliable data difficult to extract and its only advantage is possibly improved resolution in fields smaller than the range tested. The use of a larger unshielded diode is recommended for all measurements, with the additional cross-checking of data against at least one small ion chamber and film. A simple method of obtaining reliable output data from the detectors used is explained.
TL;DR: In this article, a model based on two parallel Schottky rectifiers with different barrier heights is presented, and it is shown that the excess current at low voltage can be explained by a lowering of the Schotty barrier in localized regions.
Abstract: Forward density-voltage (J-V) measurements of titanium/4H-SiC Schottky rectifiers are presented in a large temperature range. While some of the devices present a behavior in accordance with the thermionic current theory, others present an excess forward current at low voltage level. This anomaly appears more or less depending on the rectifier and on the temperature. A model based on two parallel Schottky rectifiers with different barrier heights is presented. The characteristics show good agreement. It is shown that the excess current at low voltage can be explained by a lowering of the Schottky barrier in localized regions. A proposal for the physical origin of these low barrier height areas is given.
01 Jan 1999
TL;DR: In this article, the effect of diode reverse recovery on the turn-on losses of a fast WARP/sup TM/IGBT was compared with state-of-the-art silicon diodes.
Abstract: Recent progress in silicon carbide (SiC) material has made it feasible to build power devices of reasonable current density This paper presents recent results including a comparison with state-of-the-art silicon diodes Switching losses for two silicon diodes (a fast diode, 600 V, 50 A, 60 ns Trr), an ultra-fast silicon diode (600 V, 50 A, 23 ns Trr) and a 4H-SiC diode (600 V, 50 A) are compared The effect of diode reverse recovery on the turn-on losses of a fast WARP/sup TM/ IGBT are studied both at room temperature and at 150/spl deg/C At room temperature, SiC diodes allow a reduction of IGBT turn-on losses by 25% compared to ultra-fast silicon diodes and by 70% compared to fast silicon diodes At 150/spl deg/C junction temperature, SiC diodes allow a turn-on loss reduction of 35% and 85% compared to ultra-fast and fast silicon diodes respectively The silicon and SiC diodes are used in a boost power converter with the WARP/sup TM/ IGBT to assess the overall effect of SiC diodes on the power converter characteristics Efficiency measurements at light load (100 W) and full load (500 W) are reported Although SiC diodes exhibit very low switching losses, their high conduction losses due to the high forward drop dominate the overall losses, hence reducing the overall efficiency Since this is an ongoing development, it is expected that future prototypes will have improved forward characteristics
TL;DR: In this paper, an analytical model for tunneling-enhanced recombination current in the space charge region of semiconductor junctions is presented, where the authors investigate currentvoltage characteristics of different types of Cu(In, Ga)Se2-based heterojunction solar cells in a temperature range from 100 to 340 K.
Abstract: This letter presents an analytical model for tunneling-enhanced recombination current in the space charge region of semiconductor junctions. We investigate current–voltage characteristics of different types of Cu(In, Ga)Se2-based heterojunction solar cells in a temperature range from 100 to 340 K. The temperature dependence of the saturation current and of the diode ideality factor of these devices are well described by the closed form expressions derived by the present approach.
21 Oct 1999-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the spectral properties of Cadmium telluride (CdTe) detectors, fabricated in the form of a Schottky CdTe diode, were reported.
Abstract: We report a significant improvement of the spectral properties of cadmium telluride (CdTe) detectors, fabricated in the form of a Schottky CdTe diode. With the use of high quality CdTe wafer, we formed a Schottky junction by evaporating indium on the Te-face and operated the detector as a diode. This allows us to apply much higher bias voltage than was possible with the previous CdTe detectors. A 2 mm×2 mm detector of thickness 0.5 mm, when operated at a temperature of 5°C, shows leakage current of only 0.2 and 0.4 nA for an operating voltage of 400 and 800 V, respectively. We found that, at a high-electric field of several kV cm−1, the Schottky CdTe diode has very good energy resolution and stability, suitable for astronomical applications. The broad low-energy tail, often observed in CdTe detectors due to the low mobility and short lifetime of holes, was significantly reduced by the application of a higher bias voltage which improves the charge collection efficiency. We achieved very good FWHM energy resolution of 1.1% and 0.8% at energies 122 and 511 keV, respectively, without any rise time discrimination or pulse height correction electronics. For the detection of hard X-rays and gamma-rays above 100 keV, we have improved the detection efficiency by stacking a number of thin CdTe diodes. Using individual readout electronics for each layer, we obtained high detection efficiency without sacrificing the energy resolution. In this paper, we report the performance of the new CdTe diode and discuss its proposed applications in future hard X-ray and gamma-ray astronomy missions.