Ferroelectric and pyroelectric properties of polycrystalline La-doped HfO2 thin films

Lanthanum has been identified as a promising dopant to achieve ferroelectricity in HfO2 thin films in recent theoretical and experimental studies. In this work, the pyroelectric properties of 10 nm thick polycrystalline La-doped HfO2 layers manufactured by thermal atomic layer deposition are assessed employing a sinusoidal temperature profile. Compared to Si doping, La offers a broader dopant range in which ferroelectric behavior is obtained, making the material interesting for large-scale integration and deposition on area-enhanced substrates. Pyroelectric coefficients of up to −80 μC/m2 K are obtained using an optimized stoichiometry, which is comparable to earlier measurements with Si-doped HfO2 samples. Phase-sensitive evaluation of the measured current confirms the pyroelectric origin with minimal spurious contributions. The results are discussed with respect to the ferroelectric switching behavior, which is analyzed employing first-order reversal curve measurements. It is found that there is no simple linear relationship between the remanent polarization and the pyroelectric coefficient. Experimental evidence indicates that the pyroelectric response in polycrystalline thin films is modulated by internal bias fields, which can arise from charged defects. This illustrates the need for careful tuning of the manufacturing conditions and the film phase composition in future applications such as pyroelectric sensors, energy harvesting, or solid-state cooling.Lanthanum has been identified as a promising dopant to achieve ferroelectricity in HfO2 thin films in recent theoretical and experimental studies. In this work, the pyroelectric properties of 10 nm thick polycrystalline La-doped HfO2 layers manufactured by thermal atomic layer deposition are assessed employing a sinusoidal temperature profile. Compared to Si doping, La offers a broader dopant range in which ferroelectric behavior is obtained, making the material interesting for large-scale integration and deposition on area-enhanced substrates. Pyroelectric coefficients of up to −80 μC/m2 K are obtained using an optimized stoichiometry, which is comparable to earlier measurements with Si-doped HfO2 samples. Phase-sensitive evaluation of the measured current confirms the pyroelectric origin with minimal spurious contributions. The results are discussed with respect to the ferroelectric switching behavior, which is analyzed employing first-order reversal curve measurements. It is found that there is no simp...

[1]  H. Rietveld.  Line profiles of neutron powder-diffraction peaks for structure refinement , 1967 .

[2]  A. Shaulov,et al.  Internal bias effects on pyroelectric measurements near the Curie temperature in triglycine sulphate , 1976 .

[3]  Edward J. Sharp,et al.  Use of low‐frequency sinusoidal temperature waves to separate pyroelectric currents from nonpyroelectric currents. Part II. Experiment , 1982 .

[4]  Jerry Shaw,et al.  Standardized ferroelectric capacitor test methodology for nonvolatile semiconductor memory applications , 1993 .

[5]  Hiroshi Iwai,et al.  Suppression of oxygen vacancy formation in Hf-based high-k dielectrics by lanthanum incorporation , 2007 .

[6]  U. Böttger,et al.  Ferroelectricity in hafnium oxide thin films , 2011 .

[7]  Interaction of oxygen vacancies and lanthanum in Hf-based high-k dielectrics: an ab initio investigation. , 2011, Journal of physics. Condensed matter : an Institute of Physics journal.

[8]  R. Hoffmann,et al.  Nanosecond Polarization Switching and Long Retention in a Novel MFIS-FET Based on Ferroelectric $\hbox{HfO}_{2}$ , 2012, IEEE Electron Device Letters.

[9]  C. Hwang,et al.  Evolution of phases and ferroelectric properties of thin Hf0.5Zr0.5O2 films according to the thickness and annealing temperature , 2013 .

[10]  Christopher R. Bowen,et al.  Pyroelectric materials and devices for energy harvesting applications , 2014 .

[11]  C. S. Hwang,et al.  Thin HfxZr1‐xO2 Films: A New Lead‐Free System for Electrostatic Supercapacitors with Large Energy Storage Density and Robust Thermal Stability , 2014 .

[12]  Alfred Kersch,et al.  The Origin of Ferroelectricity in Hf$_{x}$ Zr$_{1-x}$ O$_2$: A Computational Investigation and a Surface Energy Model , 2015 .

[13]  Thomas Mikolajick,et al.  Ferroelectricity and Antiferroelectricity of Doped Thin HfO2‐Based Films , 2015, Advanced materials.

[14]  Patrick Polakowski,et al.  Ferroelectricity in undoped hafnium oxide , 2015 .

[15]  Christoph Adelmann,et al.  Stabilizing the ferroelectric phase in doped hafnium oxide , 2015 .

[16]  Michael Hoffmann,et al.  Complex Internal Bias Fields in Ferroelectric Hafnium Oxide. , 2015, ACS applied materials & interfaces.

[17]  H. Funakubo,et al.  Impact of mechanical stress on ferroelectricity in (Hf0.5Zr0.5)O2 thin films , 2016 .

[18]  Stefan Slesazeck,et al.  Physical Mechanisms behind the Field‐Cycling Behavior of HfO2‐Based Ferroelectric Capacitors , 2016 .

[19]  Jacob L. Jones,et al.  A comprehensive study on the structural evolution of HfO2 thin films doped with various dopants , 2017 .

[20]  T. Leisegang,et al.  How to measure the pyroelectric coefficient , 2017 .

[21]  Mark A. Rodriguez,et al.  Pyroelectric response in crystalline hafnium zirconium oxide (Hf1-xZrxO2) thin films , 2017 .

[22]  Mark A. Rodriguez,et al.  Thickness scaling of pyroelectric response in thin ferroelectric Hf1−xZrxO2 films , 2018, Applied Physics Letters.

[23]  T. Mikolajick,et al.  Pyroelectricity of silicon-doped hafnium oxide thin films , 2018 .

[24]  Wenke Weinreich,et al.  Layer thickness scaling and wake-up effect of pyroelectric response in Si-doped HfO2 , 2018 .

[25]  Thomas Mikolajick,et al.  Al-, Y-, and La-doping effects favoring intrinsic and field induced ferroelectricity in HfO2: A first principles study , 2018 .

[26]  Lei Zhang,et al.  Pyroelectric and electrocaloric effects in ferroelectric silicon-doped hafnium oxide thin films , 2018, Physical Review Materials.

[27]  B. Hanrahan,et al.  Accounting for the various contributions to pyroelectricity in lead zirconate titanate thin films , 2018 .

[28]  J. Íñiguez,et al.  A rhombohedral ferroelectric phase in epitaxially strained Hf0.5Zr0.5O2 thin films , 2018, Nature Materials.

[29]  Jacob L. Jones,et al.  Lanthanum-Doped Hafnium Oxide: A Robust Ferroelectric Material. , 2018, Inorganic chemistry.

[30]  M. Czernohorsky,et al.  CMOS Compatible Pyroelectric Applications Enabled by Doped HfO2 Films on Deep-Trench Structures , 2018, 2018 48th European Solid-State Device Research Conference (ESSDERC).

[31]  Joshua Wilbur,et al.  Pyroelectric energy conversion with large energy and power density in relaxor ferroelectric thin films , 2018, Nature Materials.

[32]  M. Czernohorsky,et al.  Frequency domain analysis of pyroelectric response in silicon-doped hafnium oxide (HfO2) thin films , 2018, Applied Physics Letters.

[33]  Kunwoo Park,et al.  Ferroelectric Polarization-Switching Dynamics and Wake-Up Effect in Si-Doped HfO2. , 2018, ACS applied materials & interfaces.

[34]  W. Weinreich,et al.  High-density energy storage in Si-doped hafnium oxide thin films on area-enhanced substrates , 2019, Journal of Vacuum Science & Technology B.