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Indium (In) inclusions have been found in 〈100〉 indium phosphide (InP) single crystals grown in In-rich melt by the liquid-encapsulated Czochralski (LEC) method. Two kinds of In inclusions with different morphologies, one is lath-like and the other is polyhedral, have been observed. Most of the In inclusions are lath-like and their long sides are always parallel to the $$[0\overline{1}1]$$ or $$[0{\overline{1}}{\overline{1}}]$$ orientation. In (100) InP wafers, these inclusions mainly distribute in two regions viz., center of the wafer and annular belt at a certain distance from the center. These special distributions of In inclusions in InP crystals were found in our experiments for the first time. In order to clarify the cause of the special distributions of In inclusions, numerical simulations have been carried out on the melt convection in the process of InP crystal growth. The results show that the rotations of crystal and crucible significantly affect the number and direction of convection cells in the melt, which have a great influence on the enrichment and distribution of excess In at the solid–liquid interface. Different melt convections modify the radial distributions of excess In atoms near the solid–liquid interface and result in different radial distributions of In inclusions in the crystals.

In this paper, indium (In)-rich second-phase particles are observed in InP crystals, which is induced by the loss of phosphorus (P) during polycrystalline melting. Their characterizations reveal that the size of these In-rich particles is 200 nm–20 µm. The dislocation structure surrounding the second-phase particle and its formation is explained by the model of prismatic dislocation loop. The indium-rich second-phase particles could be eliminated under P-rich condition by a rapid in situ P injection before crystal growth. Excessive P injection will lead to the formation of P pores with internal P deposits. The optimal injection value is given to eliminate the defects.

Positron lifetime measurements have been carried out on liquid-encapsulated Czochralski-grown undoped InP samples sliced from the middle part of ingots over the temperature range 10–300 K. And at 70 K, the spectra have been measured in darkness, under illumination of infrared LED, and with illumination off is one sample. The measurements at low temperature reveal different concentration of hydrogen indium vacancy complex VInH4 in these samples. A relatively higher concentration of VInH4 in samples grown from P-rich undoped InP melts can be shown. The increase of resistivity of these samples can be speculated when temperature is low enough.

FTIR spectroscopy measurements indicate a presence of high concentration hydrogen existing in the liquid encapsulated Czochralski grown undoped InP wafers. These undoped InP can be annealed to be semi-insulating (SI) reproducibly. Hydrogen can facilitate the formation of anti-site defects in InP and can also induce electrically-active hydrogen related defects. The annealed behavior of InP is proved possible to be originated from the neutralization effect of hydrogen that is supplied by the dissociation of hydrogen complexes in the process of annealing. The process of hydrogen passivation of donors is discussed. Besides neutralizing impurities and defects in InP, hydrogen induces new hydrogen related defects in the band gap, and can also activate the formation of complexes involving P In , so it plays an important role in the charge compensation process in SI InP obtained by high temperature annealing.

Undoped and Fe-doped liquid encapsulated Czochralski (LEC) InP has been studied by Hall effect, current–voltage (I–V), and infrared absorption (IR) spectroscopy. The results indicate that a native hydrogen vacancy complex donor defect exists in as-grown LEC InP. By studying the IR results, it is found that the concentration of this donor defect in Fe-doped InP is much higher than that in undoped InP. This result is consistent with the observation that a much higher concentration of Fe2+ than the apparent net donor concentration is needed to achieve the semi-insulating (SI) property in InP. By studying the I–V and IR results of Fe-doped InP wafers sliced from different positions on an ingot, the high concentration of Fe2+ is found to correlate with the existence of this hydrogen complex. The concentration of this donor defect is high in wafers from the top of an ingot. Correspondingly, a higher concentration of Fe2+ can be detected in these wafers. These results reveal the influence of the complex defect o...

A hydrogen indium vacancy complex V In H 4 in undoped and Fe-doped liquid encapsulated Czochralski (LEC) InP is measured by infrared absorption spectroscopy in wafers sliced from the seed-end, middle and tail of an ingot. The concentration of V In H 4 is found much lower in wafers sliced from the ingot tail. The concentration of V In H 4 in Fe-doped InP is higher than that of the undoped InP. The concentration change of V In H 4 in an InP ingot is qualitatively in agreement with the mass action law expectation based on defect reactions. The influence of this complex on the electrical properties of n-type LEC undoped and Fe-doped InP is discussed. The high concentration of V In H 4 in the seed-end of an InP ingot correlates with two facts. The first is the high threshold concentrations of Fe and Zn required to get semi-insulating and p-type material, respectively. The second is that there is a large thermally induced reduction of carrier concentration in seed-end InP wafers than that of wafers from the ingot tail. The results reveal the influence of V In H 4 on the thermal stability of InP material due to the fact that the bond of hydrogen complex is weak and dissociates easily upon annealing. This dissociation has a relationship with the defects formed in high-temperature annealed InP, which are involved in the electrical compensation.

A large quantity of high purity InP crystal material has been produced by the phosphorus in-situ injection synthesis. In the injection method, phosphorus reacts with indium very quickly so that the rapid polycrystalline synthesis is possible. The injection speed, melt temperature, phosphorus excess, and so on are also important for a successful synthesis process. About 3200-4800 g stoichiometric high purity poly InP is synthesized reproducibly by improved P-injection method in the high-pressure puller. Twin-Free InP single crystals with diameter of 50-110 mm can be pulled after the synthesis. In the present work, the characterization of InP polycrystalline was studied by van der Pauw method, GDMS, and PL.

P-rich, In-rich and stoichiometric undoped InP melts have been synthesized by phosphorus in-situ injection method, InP crystal ingots have been grown from these melts by LEC method. The difference in these InP crystal should be attributed to the change of stoichiometry. Some samples from these ingots have been characterized by the Hall effect and Fourier transform infrared (FT-IR) spectroscopy measurements respectively. The Hall effect measurement results indicate that the carrier concentration of P-rich undoped InP is higher than that of In-rich and stoichiometric undoped InP materials. The intensive absorption peaks indicate that our phosphorus in-situ injection synthesis LEC undoped InP materials have relatively high concentration of hydrogen related complexes. The FT-IR results are also in agreement with the carrier concentration of InP grown from different stoichiometric melts.

Semi-Insulating InP is used in microelectronics devices and integrated opto-electronic circuits. The Chinese InP research team used a direct P-injection synthesis and LEC crystal growth method to prepare polycrystalline InP and to grow the undoped InP and Fe-doped SI-InP single crystal in the same puller. We can get very low concentration silicon in the ingots by using this method. And in the InP crystal the main impurity is silicon, which acts as a shallow donor in the crystal. The undoped InP has been found to be annealed into SI material around 900/spl deg/C. The Chinese InP research team present a model to explain the possible mechanisms of the Semi-Insulating behavior of bulk InP material. The physical properties of SI-InP have been studied. We have combined a variety of techniques such as FT-IR, PICTS, Hall, TDH, PL, PAS, and GDMS to investigate SI-InP. Most of the data can be explained by this model. Furthermore we compared the results of the MOCVD material, which grow on the annealed undoped SI-InP and on Fe-doped SI-InP.

High purity InP is necessary for the preparation of high quality InP single crystal especially low Fe content semi-insulating and annealed undoped semi-insulating InP single crystal. In-situ phosphorus injection synthesis of InP has several advantages over the two-step process of compounding and growing in separate furnace. In 1982 it was reported by our group that around 500g InP was synthesized and semi-insulating InP single crystals grown in one step in 30-60 minutes. A large high pressure puller have been set up, which can be used to synthesize and grow large diameter InP single crystal in our laboratory. Now 3400g InP can be synthesized reproducible and single crystals can be grown in the puller. The red phosphorus used for synthesis is contained in two vessels, which can be manipulated separately during the synthesis process. The two phosphorus vessels are heated by the auxiliary heater and the phosphorus vapour is injected into the indium melt in the crucible. We have developed a process for the rapid synthesis of InP. The whole synthesis process only needs 60-70 minutes. The synthesized InP could be indium-rich, stoichiometric or phosphorus-rich which depend on the quantity of excess phosphorus and other conditions such as the temperature of indium melt in the crucible, the thermal field, phosphorus injection speed etc. After the synthesis, InP crystal can be pulled by the conventional LEC method. Twin-free 3-inch and 4-inch InP single crystal can be obtained. The InP single crystal wafer is cut from the ingot for the measurement of electronic parameters. The carrier concentration of P-injection in-situ synthesis InP at T = 300 K is n = 2 /spl times/ 10/sup 15/ - 10/sup 16/ cm/sup -3/, the mobility is 3500 4900 cm/sup 2//Vs. These depend on the raw materials used. At T = 77 K the best result n = 2.36 /spl times/ 10/sup 15/ cm/sup -3/, the mobility is 4.8 /spl times/ 10/sup 4/ cm/sup 2//Vs. This kind of InP can be made semi-insulating with high temperature annealing or low iron doping levels.

Undoped liquid encapsulated Czochralski (LEC) InP samples have been studied by Hall effect, glow discharge mass spectroscopy (GDMS) and infrared absorption spectroscopy. A systematic discrepancy has been found between the Hall electron concentration and net donor concentration measured by GDMS. The electron concentration is always higher than the net shallow donor concentration by about (3-6)/spl times/10/sup 15/ cm/sup -3/. A hydrogen indium vacancy complex donor defect V/sub In/H/sub 4/ was detected regularly by infrared absorption spectroscopy in all undoped LEC InP samples. The fact can be explained by taking into account the existence of the donor defect in as-grown undoped LEC-InP.