1-12
TG-120 Gallium-Aluminum-Arsenide Diodes
Series TG-120 Gallium-Aluminum-Arsenide Diodes*
•
Voltage-temperature
characteristics are
monotonic over the useful
temperature range from
1.4 K to 500 K.
Excellent sensitivity
(dV/dT) at temperatures
below 50 K, making it an
ideal replacement for
older design GaAs diode
temperature sensors
Relatively low magnetic
field dependence,
∆T/T
< 4% for B < 5 T and
T > 4.2 K
The TG-120 gallium-aluminum-arsenide
(GaAlAs) diode temperature sensors are
particularly well suited for low to moderate
magnetic field applications at low
temperatures. The GaAlAs sensing element
exhibits high sensitivity (dV/dT) at low
temperatures. Voltage-temperature
characteristics are monotonic over the
sensor’s useful range from 1.4 K to 500 K
(see plots below).
Gallium aluminum arsenide diodes are direct
band-gap, single junction devices that produce
small output variances in the presence of
magnetic fields. Consequently, their low
magnetic field dependence makes them
ideally suited for applications in moderate
magnetic fields up to five tesla.
Typical Magnetic Field-Dependent
Temperature Errors
∆T/T
(%)
at B (magnetic induction)
Package Perpendicular to Field
B (tesla)
1
2
3
4
3.8
0.2
<0.1
-0.1
3.7
0.3
0.17
-0.1
2.8
0.3
0.16
-0.1
TG-120PL
•
TG-120P
GaAlAs Diodes
•
TG-120-SD
* Patent # 4,643,589, “Thermometry
Employing Gallium Aluminum Arsenide Diode
Sensor” Lake Shore Cryotronics, Inc.
See the Reference Section
for a detailed description of
Installation
Uncalibrated sensors
Calibrated sensors
CalCurve™
Sensor packages
T(K)
5
1
0.2
0.1
-0.1
4.2
2.9
30
0.2
78
<0.1
300
-0.1
When junction is parallel to B, induced errors are
typically less than, or on the order of, those shown.
Accessories suggested for installation
(see Section 3):
Stycast
®
Epoxy
Apiezon
®
Grease
IMI-7031 Varnish
Indium Solder
90% Pb, 10% Sn Solder
Phosphor-Bronze Wire
Manganin Wire
CryoCable™
For information on Packages
for Sensor Installation,
see pages 1-40 to 1-42.
Adding lead length to
sensors - see page 1-43.
Typical Voltage and Sensitivity values for GaAlAs Diodes. See page A-52 for tabular data.
Lake Shore
¤
(614) 891-2244
Fax:
(614) 818-1600
www.lakeshore.com EMail:
sales@lakeshore.com
TG-120 Gallium-Aluminum-Arsenide Diodes
1-13
Specifications
Temperature
Useful range
Minimum
Maximum
Maximum storage temperature
Standard curve
Voltage (typical)
Sensitivity (typical)
Dimensionless sensitivity (typical)
Repeatability
Accuracy (interchangeability)
Accuracy (SoftCal™)
Accuracy (calibrated)
Stability
Short-term
Long-term (per year)
Thermal response time (typical)
Recommended recalibration schedule
Excitation
Recommended
Maximum reverse voltage (diode)
Maximum forward current (diode)
Maximum power before damage
Dissipation at rated excitation
Units range (volts or ohms)
Lead wire configuration (polarity)
Physical Specifications
Materials in the sensor/construction
TG-120P
TG-120PL
TG-120-SD
1.4 K
1.4 K
1.4 K
325 K
325 K
500 K
(1)
305 K
305 K
305 K
Not available
Not available
Not available
5.200 V at 4.2 K; 1.420 V at 77 K; 0.900 V at 305 K (all models)
-180 mV/K at 4.2 K; -1.4 mV/K at 100 K; -2.8 mV/K at 300 K (all models)
See Reference Section
See Reference Section
See Reference Section
Repeatability to better than ±50 mK is required over four thermal cycles. Repeatability is typically better
than ±10 mK (all models).
None
None
None
Not applicable
Not applicable
Not applicable
±50 mK
±50 mK
±50 mK
±10 mK at 4.2 K
±10 mK at 4.2 K
±15 mK at 4.2 K
±15 mK at 4.2 K
±50 mK at 77 K
±50 mK at 77 K
±50 mK at 330 K
±50 mK at 330 K
100 ms at 4.2 K; 250 ms at 77 K; 3 seconds at 305 K
Annual
Annual
10
µA
±0.05%
10
µA
±0.05%
2 volts
2 volts
500
µA
500
µA
2 mW
2 mW
50
µW
max. at 4.2 K; 14
µW
at 77 K; 10
µW
at 300 K (typical all models)
0 to 6 volts
0 to 6 volts
Short lead positive,
Short lead positive,
long lead negative.
long lead negative.
BeO ceramic header set into a
gold-plated copper cylinder.
2.8 mm long x 3 mm diameter
79 milligrams
0.15 mm diameter x 25 mm long
0.15 mm diameter x 19 mm long
Two (2)
Phosphor-bronze, insulated
Heavy build Polyimide
Air
Constructed with platinum,
Stycast® epoxy, alumina.
1.6 mm long x 1.1 mm max. thickness
20 milligrams
0.25 mm x 0.05 mm x 19 mm long
0.25 mm x 0.05 mm x 16 mm long
Two (2)
Platinum
None
Solid epoxy
±10 mK at 4.2 K
±15 mK at 4.2 K
±50 mK at 77 K
±50 mK at 330 K
<10 ms at 4.2 K
Annual
10
µA
±0.05%
2 volts
500
µA
2 mW
0 to 6 volts
Positive lead on right with package
lid up and leads towards user.
Sapphire base with alumina
body and lid. Molybdenum, manganese
metallization on base and lid top with
nickel and gold plating.
1 mm x 1.9 mm x 3.2 mm long
38 milligrams
0.25 mm x 0.05 mm x
≈19
mm long
0.25 mm x 0.05 mm x
≈19
mm long
Two (2)
Platinum, welded to pkg.
None
Hermetically sealed in vacuum
See Reference Section
Insensitive
Can be significant
(2)
GaAlAs Diodes
Size
Mass
Leads
Size
Cathode
Anode
Number
Material
Insulation
Internal atmosphere
Environmental
Radiation effects
Magnetic fields
ESD sensitivity
Noise sensitivity
See Reference Section
See Reference Section
Recommended for use up to 5 tesla (all models)
Insensitive (Bipolar device)
Insensitive
Can be significant
(2)
Can be significant
(2)
(1) The TG-120-SD has not been tested at 500 K to determine long term stability.
(2) See the application note titled "Measurement system induced errors in diode thermometry,"
Rev. Sci. Instrum. 57 (4),
April 1986. Lake Shore order number 1420.
Ordering Information
GaAlAs Diode
Calibration Range Suffix Codes
Numeric figure is the low end of the calibration.
Letter corresponds to high end: B = 40 K, D = 100 K, L = 325 K, H = 475.
1.4B
1.4D
1.4L
1.4H
4B
4D
4L
4H
70L
70H
Model number
TG-120P
TG-120PL*
TG-120-SD
TG-120-CO
TG-120-CU
Uncalibrated sensor
Specify the Model number in the left column only,
for example TG-120P.
Calibrated sensor
Add Calibration Range Suffix Code to the end of
the Model number, for example TG-120P-1.4L.
Accessories available for sensors
ECRIT
Expanded interpolation table
SCR
Special calibration report
8000
Calibration report on floppy disk
COC-SEN
Certificate of conformance
Other packages available through special order. Please consult Lake Shore.
See page 1-41 for additional adaptors.
* Below 10 K, calibration is valid in a vacuum only.
When ordered with Lake Shore temperature controllers, these diodes should be ordered as calibrated
sensors in order to read temperature.
Lake Shore
¤
(614) 891-2244
Fax:
(614) 818-1600
www.lakeshore.com EMail:
sales@lakeshore.com
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