M. Bockowski - Academia.edu (original) (raw)

Papers by M. Bockowski

physica status solidi (b)

Journal of Applied Physics

MRS Internet Journal of Nitride Semiconductor Research

We present recent results on bulk GaN crystallization. The best quality GaN crystals grown from t... more We present recent results on bulk GaN crystallization. The best quality GaN crystals grown from the solution at high N2 pressure without an intentional seeding are single crystalline platelets of stable morphology reaching dimensions up to 10 mm. The fastest growth direction for such crystals is [1 0 0], perpendicular to the GaN c-axis. The maximum stable growth rate perpendicular to crystal c-axis is determined from the experiment and used for an estimate of the effective supersaturation for the {10 0} face assuming two dimensional layer growth. The heat of GaN disssolution, determined from experimental solubility data, is used for the estimation of the edge energy of 2-D nuclei on the growing {10 0} face. Bulk crystal growth seeded by a single hexagonal needle with well developed {10 0} faces is also reported. The crystallization mechanisms and morphological stability in seeded growth of GaN are discussed on the basis of experimental results. The physical properties of the GaN cry...

MRS Internet Journal of Nitride Semiconductor Research, 1996

GaN epitaxial layers on GaN single crystals were grown using molecular beam epitaxy with an NH3 s... more GaN epitaxial layers on GaN single crystals were grown using molecular beam epitaxy with an NH3 source. The deposited layers were examined by high resolution x-ray diffraction and photoluminescence (PL) spectroscopy. We observed strong and extremely narrow (half-widths of 0.5 meV) lines related to the bound excitons. In the higher energy range we observed three strong lines. Two of them are commonly attributed to free exciton transitions A (3.4785 eV) and B (3.483 eV). Their energetic positions are characteristic of strain-free GaN material.

MRS Internet Journal of Nitride Semiconductor Research, 2004

We used single crystals of GaN, obtained from high-pressure synthesis, as substrates for Metalorg... more We used single crystals of GaN, obtained from high-pressure synthesis, as substrates for Metalorganics Vapor Phase Epitaxy growth of violet and UV laser diodes. The use of high-quality bulk GaN leads to the decrease of the dislocation density to the low level of 105 cm−2, i.e. two orders of magnitude better than typical for the Epitaxial Lateral Overgrowth laser structures fabricated on sapphire. The low density and homogeneous distribution of defects in our structures enables the realization of broad stripe laser diodes. We demonstrate that our laser diodes, having 15 μm wide stripes, are able to emit 1.3-1.9 W per facet (50% reflectivity) in 30 ns long pulses. This result, which is among the best ever reported for nitride lasers, opens the path for the development of a new generation of high power laser diodes.

Acta Physica Polonica A, 2002

Pr oceed in gs o f t he XXX I I n t ern at io n al Sch oo l o f Sem icond uct i ng Co m p ou n ds... more Pr oceed in gs o f t he XXX I I n t ern at io n al Sch oo l o f Sem icond uct i ng Co m p ou n ds, Ja szo wi ec 200 2 R el at ion sh i p b et w een Sam p le Mo rp h olo gy an d C arrie r Di˜u sion L en gth in G aN Th in Film s M. G od l ew sk i a , E.M. Go l d y s b , M. P hil l i ps c , T. B ot t c he r d , S. Fi gge d , D. H ommel d , R. Czer nec ki e , P. Pr yst aw k o e , M. Le szc zyn ski e , P. Pe rli n e , P. Wi snie w ski e , T. Susk i e , M. Bo ck ow sk i e , I. Gr ze go r y e and S. Po ro ws ki e a In st it ut e of P hysi cs, Po l i sh Ac ademy of Sciences al. Lo tni k §w 32/ 46, 02-668 W arsaw, Po l and b Semi cond. Sci. a nd T echnol. La b., Ma cqua ri e Uni v. , Sydney , Austra l i a c Mi crostructura l Ana l ysi s Uni t, Uni versi ty of T echnol ogy Sydney , Austra l i a d Insti tute o f Sol i d State Physi cs, Brem en Uni versi ty , G erm any e Hi gh Pressure Res. Center (Uni press), Po l i sh Aca d. Sci., W arsaw, Po l and Scann ing and spot-mo de cat ho dol umi nescence investigations of homoand hetero-epita xial GaN Ùlms indicate a surprising ly small in Ûuence of their microstructure on overall intensity of a light emission. T his w e explain by a correlation betw een structural quality of these Ùlms and di˜usion length of free carriers and excitons. Di˜usi on length increases with impro vi ng structural quality of the samples , w hich, in turn, enhances the rate of nonradiati ve recombination on structural def ects, such as dislo cati on s.

Gallium Nitride Materials and Devices, 2006

Growth of GaN under pressure from solution in gallium results in almost dislocation free plate-li... more Growth of GaN under pressure from solution in gallium results in almost dislocation free plate-like crystals but with size limited to app. 1-2 cm (lateral) and 100 µm (thickness) or up to about 1cm long needles. Deposition of GaN by HVPE on the pressure grown seeds allows stable crystallization (in terms of flatness of the crystallization front and uniformity of the new grown material) at a rate of about 100 µm/h on both types of seed crystals. However, in the thick GaN crystals grown on almost dislocation free plate-like substrates quite a high number of dislocations appears if the crystal thickness exceeds certain critical value. Since the critical thickness for defect generation is of the order of 100 µm, almost dislocation free layers (density below 10 4 cm-2) thinner than 100 µm can be grown. The most obvious further step is removing the substrate and continuation of the HVPE deposition on the free standing low dislocation density layer of sub-critical thickness. The pressure grown substrates were removed by mechanical polishing or conductivity sensitive electrochemical etching (for strongly n-type substrates). Then the HVPE low dislocation density GaN 1 platelets were used as substrates for the growth of a few mm thick bulk GaN crystals. The crystals were characterized by defect selective etching of both polar (0001) and non-polar (10⎯10) surfaces to check presence and distribution of structural defects. The X-ray measurements allowed concluding about character of strain and deformation in high pressure GaN-HVPE GaN system.

MRS Proceedings, 1996

Bulk single crystals of GaN were used for epitaxial growth of GaN films by molecular beam epitaxy... more Bulk single crystals of GaN were used for epitaxial growth of GaN films by molecular beam epitaxy. Low temperature photoluminescence yields much higher intensity emission in the near bandedge region for epitaxial films with respect to the situation in bulk crystals. Character of this luminescence changes also. Dominant band-to-band transitions in the bulk crystals are exchanged by bound exciton and/or donor-acceptor pair transitions observed in the epitaxial layers. We will compare the obtained results with the available data on the homoepitaxial samples grown by metalorganic chemical vapor deposition method and discuss the importance of establishing the basic information on energetic positions of excitonic transitions in stress free samples.

Japanese Journal of Applied Physics, 2014

ABSTRACT Results of GaN growth from gallium solution under high nitrogen pressure are presented. ... more ABSTRACT Results of GaN growth from gallium solution under high nitrogen pressure are presented. Basic of the high nitrogen pressure solution (HNPS) growth method is described. A new approach of seeded growth, multi-feed seed (MFS) configuration, is demonstrated. The use of two kinds of seeds: free-standing hydride vapor phase epitaxy GaN (HVPE-GaN) obtained from metal organic chemical vapor deposition (MOCVD)-GaN/sapphire templates and free-standing HVPE-GaN obtained from the ammonothermally grown GaN crystals, is shown. Depending on the seeds' structural quality, the differences in the structural properties of pressure grown material are demonstrated and analyzed. The role and influence of impurities, like oxygen and magnesium, on GaN crystals grown from gallium solution in the MFS configuration is presented. The properties of differently doped GaN crystals are discussed. An application of the pressure grown GaN crystals as substrates for electronic and optoelectronic devices is reported.

MRS Proceedings, 1997

The recent progress in high pressure crystallization of GaN is reported. The results of the growt... more The recent progress in high pressure crystallization of GaN is reported. The results of the growth from the solutions of atomic nitrogen in pure Ga and in its alloys with Mg, Ca and Zn are discussed. It is shown that the growth mechanisms and the physical properties of the crystals depend on the type of dopant added into the solution. In particular, high resistivity (104-106Ωcm) GaN crystals of improved structural quality can be grown from solutions containing Mg. It was also observed that the addition of Mg, Ca and Zn suppress yellow photoluminescence commonly observed in GaN crystals grown without an intentional doping. The preparation of surfaces of GaN substrates for homoepitaxy by mechanical and mechanochemical polishing is discussed. It is shown that atomically flat, thermally stable surfaces are possible to obtain by the applied procedures.Some most interesting results concerning homoepitaxial growth by MOCVD and MBE is shortly reviewed. In particular, it is shown that perfec...

Journal of Applied Physics, 2001

Comprehensive studies of the electrical properties of Mg-doped bulk GaN crystals, grown by high-p... more Comprehensive studies of the electrical properties of Mg-doped bulk GaN crystals, grown by high-pressure synthesis, were performed as a function of temperature up to 750 °C. Annealing of the samples in nitrogen ambient modifies qualitatively their resistivity values rho and the rho(T) variation. It was found that our material is characterized by a high concentration of oxygen-related donors and that

Solid State Communications, 1998

Temperature dependent studies of the resonant and phonon-assisted radiative recombination of free... more Temperature dependent studies of the resonant and phonon-assisted radiative recombination of free excitons (FEs) in GaN are performed and are analyzed within the polariton concept. A strong impurity scattering of exciton-polaritons is proposed to be responsible for the revealed unusual behavior of the free A exciton in GaN, i.e. an enhanced intensity of the resonant FE emission in comparison with

Journal of Crystal Growth, 2014

ABSTRACT Transmission Electron Microscopy (TEM) studies of undoped and Mg doped GaN layers grown ... more ABSTRACT Transmission Electron Microscopy (TEM) studies of undoped and Mg doped GaN layers grown on the HVPE substrates by High Nitrogen Pressure Solution (HNPS) with the multi-feed-seed (MFS) configuration are shown. The propagation of dislocations from the HVPE substrate to the layer is observed. Due to the interaction between these dislocations in the thick layers much lower density of these defects is observed in the upper part of the HNPS layers. Amorphous Ga precipitates with attached voids pointing toward the growth direction are observed in the undoped layer. This is similar to the presence of Ga precipitates in high-pressure platelets, however the shape of these precipitates is different. The Mg doped layers do not show Ga precipitates, but MgO rectangular precipitates are formed, decorating the dislocations.

Nanoepitaxy: Materials and Devices VI, 2014

Solid State Communications, 1991

ABSTRACT

Solid State Communications, 1996

In this work we report results of photoluminescence (PL) and reflectivity meas~ements in the exci... more In this work we report results of photoluminescence (PL) and reflectivity meas~ements in the exciton region of GaN homoepit~ial layers grown by metalorganic chemical vapour deposition on GaN substrates. At low temperature (4.2K), very narrow (FWHM = i.OmeV) PL lines related to excitons bound to neutral acceptor (3.4666eV) and neutral donor (3.4719eV) were observed. The energies of gee excitons fi-om re~e~ti~~ and PL measurements were found to be: E,= 3.4780eV, Ea= 3.4835eV and EC= 3.502eV.