Chemical Properties
3–12mm pieces (sintered), and -325 mesh 10μm or less with 99.999% purity; white to brown; cub or hexagonal crystal(s); hex: a=0.4309nm, c=0.7021 nm, enthalpy of fusion 305.307 kJ/mol; becomes red in sunlight; used as a red pigment, in semiconductors, and as an evaporation material and sputtering target to produce photoconductive films and infrared filters; possible use in the electrofabrication of microdiode arrays [HAW93] [MER06] [CER91] [KLE93] [KRE91]
Physical properties
The energy gap of the hexagonal CdSe obtained from the absorption measurement Eg (Γ6–Γ1 ) is E
g=1.84 eV, temperature coefficient -4.6×10
-4 eV/K, and pressure coefficient 3.7×10
-6 eV/kg–cm
-2 .
The band structure of cubic CdSe is similar to that of GaAs.
Uses
In photoconductors, semiconductors, photoelectric cells, and rectifiers; in phosphors.
Uses
Dispersions with CdS (Aldrich products
208183,
217921) deposited on glass or Si substrates results in tunable red, yellow, or green fluorescent material.
Uses
Cadmium selenide is used as a n-type semiconductor and its nanoparticles are used in laser diodes, opto-electronic devices, nanosensing, biomedical imaging and high efficiency solar cells. Since, it is transparent to infrared light, it finds application in photoresistors and windows for instruments utilizing IR light.
Definition
ChEBI: Cadmium selenide is a cadmium molecular entity.
Production Methods
A single crystal can be grown artificially through the vapor phase method or the Stockbarger method.
To obtain evaporated films, the source materials are heated in the alumina crucible with a nichrome heater. Crystal with a larger grain size is obtained at a higher substrate temperature.
The following corrosives are reported:
HNO3 (water cleansing after 2–3 s)
H2SO4 (water cleansing after 5–10 s)
18 N solution of 30 HNO3:0.1 HCl:20 H2SO4 (40℃, 8 s, cleansing with concentrated H2SO4)
3 HCl:1 HNO3
Application
Cadmium selenide is used as a photoconductive detector for λ: 0.3–0.72 mm (a sharp peak at 0.7 mm) at room temperature. The typical performances are as follows:
Peak detectivity: 2.1×10
11 cm Hz
1/2/watt, (λ: 0.7 mm)
Response time: ca. 12 ms
Intermittent frequency: 90 Hz
Dominant noise: current noise
General Description
CdSe crystal can exist in solid hexagonal or cubic structure. CdSe behaves as an n-type semiconductor, with a bandgap of 1.74 eV (300K).1
Flammability and Explosibility
Not classified
Structure and conformation
The space lattice of CdSe (Cadmium selenide) belongs to the two types of crystal system, the cubic system, with the zinc-blend type structure that has a lattice constant of a=0.605 nm, and the hexagonal system, with the wurtzite type structure that has lattice constants of a=0.430 nm and c=0.702 nm.
