High Purity InP Layers Research Articles

Room temperature particle detectors based on indium phosphide

A study of electrical properties and detection performance of particle detectors based on bulk InP and semiconducting LPE layers operated at room temperature is presented. Bulk detectors were fabricated on semi-insulating InP crystals grown by liquid-encapsulated Czochralski (LEC) technique. High purity InP layers of both n- and p-type conductivity were used to fabricate detector structures with p–n junction. The detection performance of particle detectors was measured by pulse-height spectra with alpha particles emitted from 241Am source at room temperature. Better noise properties were achieved for detectors with p–n junctions due to better quality contacts on p-type layers.

Gas source molecular beam epitaxy of InP-based microstructures: material growth, characterization and device applications

InP epitaxial layers and InGaAs/InAlAs/InP modulation doped heterostructures were grown by gas source molecular beam epitaxy, in which arsenic and phosphorus beams were obtained by thermal cracking of AsH 3 and PH 3. High purity InP layers have been obtained by optimizing growth parameters. To identify the species of impurity and defect in high quality InP layers, low temperature photoluminescence (PL) and photothermal ionization spectroscopy measurements were carried out. The residual donors were determined to be silicon and sulfur. To obtain a deep insight to the electronic subband structure of the two-dimensional electron gas (2DEG) system, Shubnikov-de Haas, quantum Hall effect measurements and field-dependent cyclotron resonance measurements were conducted. The electron density on each subband in 2DEG was determined to be 2.84×10 12 and 3.4×10 11 cm −2, respectively. The effective masses of the two subbands are (0.061±0.001) m 0 for the zero subband and (0.049±0.001) m 0 for the first subband. An optoelectronic integrated circuit (OEIC) structure consisting of high electron mobility transistor (HEMT) and metal semiconductor metal photo detector (MSM-PD) was achieved by gas source molecular beam epitaxy with one growth run. The responsibility of MSM-PD is 0.5 A/ W. DC transconductance of an InGaAs/InAlAs HEMT with 1.5-μm gate length is 305 mS mm −1; the maximum saturation current is 350 mA mm −1 and the pinch-off voltage is −1.4 V. The gain of the HEMT amplifier is 14 dB. The integrated photoreceiver could successfully operate at a data rate of 622 Mbit s −1.

Growth of InP using TBP and DTBP in metalorganic molecular beam epitaxy

The growth of high purity InP layers using trimethylindium (TMIn) and different commercial tertiarybutylphosphine (TBP) batches as well as ditertiarybutylphosphine (DTBP) as a new phosphorous precursor was studied in a production type metalorganic molecular beam epitaxy (MOMBE) growth chamber. The cracking behaviour of TBP was investigated by mass spectrometry. Increasing the beam equivalent pressure from 10 −6 Torr to growth relevant pressures in the 10 −5 Torr range, a transition of the pyrolysis regime was observed, accompanied with a reduced H 2+P 2 production and a strong formation of the hydride PH 3 and dihydride P 2H 4. This behaviour depends on the conditions on the cracker surface and indicates that the decomposition of TBP occurs by a radical formation process. At 77 K the deposited InP layers exhibited Hall mobilities better than 100 000 cm 2/V s for the use of three TBP batches from two different suppliers with a best value of 167 000 cm 2/V s at n=1.4×10 14 cm −3. The linewidth of the donor bound exciton in the 1.8 K photoluminescence spectrum of the sample with the highest electron mobility was about 0.09 meV. The first use of DTBP in MOMBE for the growth of high purity InP was also encouraging. The best value of the Hall mobility at 77 K was 77 300 cm 2/V s with n=5.1×10 14 cm −3.

Electrical, optical properties, and surface morphology of high purity InP grown by chemical beam epitaxy

High purity InP layers have been grown by chemical beam epitaxy using H2 as the carrier gas for transporting the metal alkyl trimethylindium into the growth chamber. InP layers exhibiting Hall mobility as high as 238 000 cm2/V s at 77 K and with a peak value of 311 000 cm2/V s at 50 K and residual Hall concentration of 6×1013 cm−3 at 77 K were grown at 500 °C using a low V/III ratio (2.2) and a phosphine (PH3) cracking cell temperature of 950 °C. The 4.2 K photoluminescence spectra were dominated by donor bound exciton (D0,X)n up to n=6 and free exciton (X) transitions for InP layers grown above 500 °C. All the InP samples exhibited very weak acceptor related photoluminescence transitions indicating very low concentration of acceptors. The energy of these transitions suggests that Mg is the major residual acceptor. Donor impurity identification by high resolution magnetophotoluminescence indicated that S and Si are the major impurities. PH3 has been found to be the major source of S impurities in the present study.

Chemical beam epitaxy of InP on planar and non-planar substrates

High purity InP layers have been grown by chemical beam epitaxy (CBE) using H 2 as the carrier gas for transporting the metal alkyl TMI into the growth chamber. InP layers exhibiting Hall mobility as high as 238,000 cm 2/V·s at 77 K and with a peak value of 311,000 cm 2/V·s at 50 K and residual impurity concentration of 6×10 13 cm −3 at 77 K were grown at 500°C using low V/III ratio (2.2) and PH 3 cracking cell temperature of 950°C. These values are the highest mobility values ever reported for InP grown by any molecular beam technique. Selective embedded growth (SEG) of InP and InGaAs was achieved in 2.0 μm deep trenches opened in Si 3N 4 masks on InP substrates. Overgrowth of InP on corrugated InP substrates was also achieved without damaging the surface grating profile.

Growth of high-purity InP by chemical beam epitaxy

High-purity InP layers have been grown by chemical beam epitaxy using H2 as the carrier gas for transporting the metal alkyl-trimethyl indium into the growth chamber. InP layers with μ≳1.0×105 cm2/V s and n<4.0×1014 cm−3 were grown at substrate temperatures as low as 500 °C and using a low V/III ratio (2.2) and PH3 cracking cell temperature of 900 °C. The 4 K photoluminescence spectra were dominated by donor bound excitonic transitions (D0, X)n up to n=5 and the free-excitonic (X) transitions for InP layers grown above 500 °C.

Very high purity InP layer grown by liquid-phase epitaxy using erbium gettering

Very high purity InP layers have been grown by liquid phase epitaxy using rare-earth erbium as the donor-gettering source. All the Er-doped samples still exhibit n-type conduction, but its carrier concentration decreases with increasing the Er amount into the growth solution. The 300 K electron concentration as low as 7×1013 cm−3 has been achieved on high-purity layers. By low-temperature photoluminescence measurement, the donor impurities of the InP samples have been obviously reduced due to the Er gettering. The free-exciton line with a linewidth of 0.9 meV dominates in the exciton spectra and the intensity ratio of free exciton to exciton-bound-to-neutral-donor lines exceeds 2.6 for the high-purity layers with n=7×1013 cm−3.

Very high purity InP layers grown by adduct-MOVPE

Using the adduct compound trimethylindium-trimethylphosphine (TMIn-TMP) very high purity InP layers have been grown by atmospheric pressure MOVPE (AP-MOVPE). Residual electron concentrations of less than 4 × 10 14 cm -3 and mobilities of up to 149,000 cm 2/V·s at 77 K have been obtained.

High-Purity LPE Growth of InP by Co Addition to an In–P Melt

High-purity InP layers are grown using an LPE technique with Co addition. In an In–P solution, Co combines with P to form a CoP precipitate. Solution impurities were removed by incorporation into the CoP precipitate and the In–P solution was purified as a result. High-purity InP layers with 100,000–110,000 cm2/Vs of Hall mobility at 77 K were obtained by a combination of adding the Co and baking the In–P solution in wet hydrogen.

Rare earth ions in LPE III-V semiconductors

InP : Yb LPE layers have been grown by a supercooling process at high growth temperatures up to 800°C. The Yb concentrations in the In growth melts ranged between 0.001 and 0.005 mole fraction. Photoluminescence and Hall measurements gave information about the incorporation behaviour of the rare earth ion Yb 3+ (4f 13) and about its influence on the electrical properties of InP. Time resolved photoluminescence measurements at low temperatures indicated a lifetime of about 12 μs of the excited Yb 3+ state. LPE grown InP:Yb p-n electroluminescence diodes were fabricated, which emit the intracentre Yb luminescence at 1 μm wavelength. High purity InP layers could be grown, using Yb in low concentrations to remove residual impurities from the growth melts. Net carrier concentrations N D - N A of 2 × 10 14 cm −3 at 300 K (1.5 × 10 14 cm −3 at 77 K) and carrier mobilities of 5700 cm 2/V·s at 300 K (90,000 cm 2/V·s at 77 K) could be achieved.

Improved molecular beam epitaxial growth of InP using solid sources

Molecular beam epitaxy (MBE) has been used to grow high-purity InP layers using solid sources and a graphite cracking zone to generate P2. Close control of slice temperature was achieved by mounting the substrate on a 3 in (75.6 mm) silicon wafer with indium solder. In addition, two differently packed phosphorus sources were investigated to assess the effect of oxides/water on InP purity. Several InP layers with a 77 K mobility of ~50000 cm2V?1s?1 were grown using a phosphorus source vacuum-packed at manufacture.

MOCVD growth and characterization of high quality InP

We report on the first growths of InP by low-pressure MOCVD using solid TMI as the indium source. The results equal or exceed the existing state of the art for high purity InP layers. A low pressure (0.1 atm) horizontal reactor was used to suppress possible adduct formation. A low TMI bath temperature 12.2°C was used to get stable sublimation with hydrogen carrier gas. A new reactor configuration consisting of a gas collector and a 60° inclined susceptor was used, which made growth rate and efficiency as high as 8.4 μm/h and 3832 μm/mol, respectively, even though both the TMI bath temperature and system pressure are low. The morphology of the epitaxial layers was good and thickness of the epilayers was uniform. The best room temperature and 77 K mobilities were 5366 and 131620 cm 2/V·s, respectively, for the same sample and the lowest net carrier concentration was n 300=1.1×10 14 cm −3. Th e 3.7 K photoluminescence exciton spectra exhibit fine structures and no neutral acceptor bound exciton emission was observed on the best samples indicating low impurity compensation, high quality and purity.